Chapter 2

What Is Time?

A Philosophical and Scientific Introduction for Everyone

"What then is time? If no one asks me, I know; if I wish to explain it to one who asks, I do not know."¹ With those famous words, Augustine of Hippo captured one of the deepest puzzles in all of human thought. We all know what time is — or at least we think we do. We wake up in the morning, eat breakfast, go to work, come home, and fall asleep at night. We celebrate birthdays. We remember yesterday. We plan for tomorrow. We feel time passing every single moment of our lives. Time is so woven into the fabric of our experience that it seems strange to even ask what it is.

And yet, the moment we try to pin it down — the moment we try to say exactly what time is, in a clear and precise way — it slips right through our fingers. Is time a thing? A substance? A dimension? A relationship? An illusion? A feature of our minds? A feature of the world? All of these answers have been proposed by brilliant thinkers over the centuries, and the debate is far from settled.

We experience time in so many ways that we rarely pause to notice. We feel the urgency of a deadline. We savor a beautiful moment and wish it would last. We grieve over years gone by. We eagerly anticipate what is coming. Time seems to speed up when we are having fun and slow to a crawl when we are bored. We say things like "time flies" and "time heals all wounds" and "there is never enough time" — and we know exactly what we mean, even though we cannot define what time actually is. This gap between our lived experience of time and our ability to explain it is precisely what makes the question so fascinating.

Why does this matter for a book about God and time? Because before we can ask the question at the heart of this book — "Is God in time or outside of it?" — we need to have at least a basic understanding of what time actually is. If we do not know what time is, we cannot meaningfully ask whether God experiences it, transcends it, or created it. The answer we give to the question "What is time?" will directly shape the answer we give to the question "What is God's relationship to time?"

I want to be upfront about something: this chapter covers some genuinely difficult material. Philosophy of time is one of the most challenging areas in all of philosophy, and the science of time — especially Einstein's theory of relativity — is not exactly bedtime reading. But I believe these ideas can be explained clearly and simply, and I am going to do my very best to walk us through them in a way that anyone can follow. We will not need a degree in physics or philosophy. We will need patience, a willingness to think carefully, and maybe a cup of coffee. By the end of this chapter, we will have a solid foundation for the rest of the book.

Here is our thesis for this chapter: Before we can ask whether God is in time or outside of it, we need to understand what time actually is — and this turns out to be one of the most profound and baffling questions in all of philosophy and science. We will survey the major philosophical theories of time, introduce the crucial distinction between two competing views of time's nature (the A-theory and the B-theory), briefly look at what modern physics has to say, and then explain why all of this matters enormously for theology.

The Difficulty of Defining Time

Let us start with a simple question: What is time? Try to answer it. Really try. You will find, as Augustine did, that the harder you think about it, the more elusive it becomes.

William Lane Craig opens his important book Time and Eternity with a delightful observation: "Time, it has been said, is what keeps everything from happening at once."² When you think about it, this quip is actually quite helpful. Time is whatever it is that separates events — that makes it so that breakfast comes before lunch, and lunch comes before dinner, and Tuesday comes before Wednesday. Without time, everything would happen all at once (if it could happen at all), and that is obviously not how reality works.

But this does not really tell us what time is. It tells us what time does. Craig goes on to note just how slippery the concept is. If we say that time is "duration," we are simply using another word for the same thing — duration is just a stretch of time, so we have said that time is a stretch of time. Not very helpful! If we try to define time as a dimension ordered by the relations "earlier than" and "later than," we are still stuck — because "earlier" and "later" are themselves temporal concepts. We end up going in circles.³

This circularity problem has haunted thinkers for centuries. Aristotle defined time as "the number of motion according to the before and after."⁴ But as the ancient physician Galen pointed out, you cannot define time in terms of motion with respect to "before and after" without already assuming what time is — because "before" and "after" are temporal words.⁵ R.T. Mullins puts the problem crisply: if you try to explain what time is by using the concepts of "before," "after," "change," or "succession," you have already smuggled time into your explanation. You cannot define time without using time.⁶

So should we just give up? Not at all. While a perfectly clean, non-circular definition of time may be impossible, we can still learn a great deal about time's nature by examining the competing theories that philosophers and scientists have proposed. Even if we cannot capture time in a neat definition, we can understand it better by looking at what the best minds in history have said about it. And as we will see, the theory of time we adopt has massive consequences for how we understand God.

Three Philosophical Theories of Time

Throughout the history of philosophy, three major theories about the nature of time have emerged. Each one gives a different answer to the basic question: What kind of thing is time? Is time a "thing" at all, or is it just a way of describing the relationships between things? Let us look at each theory in turn.

The Relational Theory: Time Is the Relationship Between Events

The first theory is called the relational theory of time. On this view, time does not exist on its own — it is not a separate "thing" floating out there in the universe. Instead, time is simply the ordered relationship between events. It is a way of describing how things that happen are connected to each other. No events, no time.

Think of it this way. Imagine a completely empty universe — no matter, no energy, no light, no movement, no change of any kind. On the relational theory, there would be no time in that universe. Time only exists because things happen. It is the relationship between the things that happen — this event comes before that event, which comes before the next event — and that ordered sequence is what we call "time."

Augustine leaned in this direction. In Confessions Book XI, he argues that time is measured by the changing of things, and that without creation — without a changing, physical universe — there would be no time. "Without creation there cannot possibly be time," Augustine insists.⁷ The great German philosopher Gottfried Wilhelm Leibniz (1646–1716) developed the relational theory more fully. For Leibniz, time is "nothing but the order of successive events." Strip away all the events, and there is nothing left — no invisible "container" of time just sitting there empty. Time just is the order in which things happen.⁸

Craig holds a relational view of time, and this is directly connected to his position on God and time. If time is relational — if it only exists when events occur — then before creation there were no physical events (no universe, no change, no motion). And if there were no events, there was no time. This is precisely why Craig argues that God was timeless before creation. On a relational view, there was nothing for God to be "in" before He created the world. Time simply did not exist yet.⁹

The theological implications of the relational theory are significant. If time depends on events, and if the only events that existed before creation were the inner life of the Trinity, then the question becomes: Do the intra-Trinitarian relations count as "events"? Does the Father's eternal generation of the Son count as something that "happens"? If so, then even on a relational view, there was time before creation — because there were events (divine events) before creation. This is an important point that Craig's version of the relational theory does not adequately address, and it is one reason why I ultimately find the causal theory more compelling. The eternal life of the Trinity is not static. It involves real relations, real love, real communication between three divine Persons. And if these relations are genuine, they involve a kind of sequence — even if it is not the measured, clock-driven sequence of physical time. We will explore this argument in full in Chapter 26, where we examine how perichoresis (the mutual indwelling of the Trinitarian Persons) provides a foundation for divine temporality.

The relational theory is elegant and tidy. But it faces serious problems. Mullins raises a particularly sharp one: the problem of circularity. If you say that time is just the relationship between events, you need to explain what an "event" is without using any temporal language. But a standard definition of an event is "a substance having a particular property at a particular time." Time is built right into the concept of an event! You cannot use events to explain time if events already contain time in their definition. As the philosopher Ulrich Meyer puts it, "If events are made up of times then times cannot also be made up of events."¹⁰ The relational theory seems to go in circles.

Another version of the relational theory, called event-relationalism, tries to get around this by saying we can "abstract" time from events — that is, we can build up the concept of time from the more basic concept of events happening in sequence. But as Mullins points out, even this version struggles to describe the relationships between events without sneaking in temporal words like "before," "after," or "simultaneous." Robin Le Poidevin, for example, describes event-relationalism as the view "that time is just an ordered series of events, each individual moment identified with a collection of simultaneous events."¹¹ But the word "simultaneous" is a temporal word. The circularity creeps back in.

The Substantival Theory: Time Is a "Container" That Exists Independently

The second theory is called the substantival theory of time (sometimes called the "absolute" theory). On this view, time is a real thing — a genuine feature of reality that exists whether or not anything happens in it. Time is like a container or a stage. Events happen in time, but time itself would exist even if nothing ever happened.

The most famous defender of this view was Sir Isaac Newton (1643–1727), one of the greatest scientists who ever lived. Newton wrote: "Absolute, true, and mathematical time, of itself, and from its own nature, flows equably without relation to anything external."¹² For Newton, time is like a river that flows steadily and uniformly, regardless of what is happening in the universe. You could remove every planet, star, and atom, and time would still flow. It exists "of itself, and from its own nature."

Newton saw absolute time as closely connected to God. He believed that absolute time was, in some sense, the "sensorium of God" — a dimension of God's own being through which God perceives and governs the universe. On Newton's view, God exists within this absolute time. God is temporal — He experiences the flow of time — and time itself is rooted in God's nature.¹³

The substantival theory has a significant advantage for theology: it allows God to exist "in" time even before creation. If time is a real container that exists independently of events, then time could have existed before the physical universe — and God could have been "in" time all along. There is no need to posit a timeless phase in God's existence, because time was already there (or was itself a feature of God's being).

Mullins notes that this identification of absolute time with an aspect of God's being is not a fringe idea. It is represented in Western thinkers like Henry More, Isaac Newton, and Samuel Clarke.¹⁴ These thinkers saw time not as something created by God, but as something that flows from God's own nature — much as light radiates from the sun.

The substantival theory faces its own challenges, of course. Leibniz famously objected that if time is an independent container, then God's decision to create the universe at one moment rather than another would be arbitrary. Why did God create the world when He did, rather than a thousand years earlier or a thousand years later? If time has been flowing evenly forever, every moment is exactly like every other moment — there is no reason to prefer one over another. This seems to violate the Principle of Sufficient Reason (the principle that everything must have a reason or explanation). Leibniz argued that the relational theory avoids this problem because, on the relational view, there is no "before" creation — creation is simply the first event, and time begins with it.¹⁵

This debate between Newton and Leibniz — carried out through their famous correspondence (with Samuel Clarke acting as Newton's spokesperson) — is one of the most important exchanges in the entire history of the philosophy of time, and we will encounter it again later in the book (see Chapter 14). For now, the key point is that the substantival theory sees time as a real, independent feature of reality, and this view naturally leads to a picture of God who exists within time.

The Causal Theory: Time Is Grounded in Causation

The third theory is called the causal theory of time, and it offers a creative alternative to both the relational and substantival views. On this theory, time is grounded in causation — in the relationship between causes and their effects. Wherever there is causation, there is time. The order of time is the order of causes.

The philosopher Garrett DeWeese provides the most thorough defense of this view in his book God and the Nature of Time. DeWeese argues that time is "dynamic and causal in nature" — that causation explains why time flows, and in which direction it flows.¹⁶ Think about it this way: causes always come before their effects. When you strike a match, the striking (the cause) comes before the flame (the effect). When you drop a ball, the release (the cause) comes before the fall (the effect). This causal ordering — cause first, effect second — is what gives time its direction and its flow.

DeWeese notes that the causal theory has a powerful advantage: it can explain three features of time that any good theory of time must account for. First, it explains the flow of time — why time moves forward rather than standing still. Second, it explains the direction of time — why time moves from past to future rather than from future to past. And third, it can account for temporal distance — how we measure the "length" of time between events.¹⁷

The causal theory is especially important for theology because of what it implies about God's inner life. If time is grounded in causation, and if the persons of the Trinity stand in causal relations to one another — the Father eternally loves the Son, the Son eternally responds to the Father, the Spirit eternally proceeds from the Father and the Son — then there is a causal order within the divine life itself. And where there is causation, there is time. This means the Trinity generates a form of temporality even apart from creation. God has always been temporal, because the Father has always been causing (generating) the Son, and the Spirit has always been proceeding from the Father and the Son.¹⁸

I find the causal theory very attractive, in large part because of this theological implication. As we will see in Chapter 26, the intra-Trinitarian perichoretic relations — the mutual indwelling and dynamic interaction of the three divine Persons — provide a powerful foundation for divine temporality. The causal theory of time gives us the philosophical framework to make this case.

DeWeese himself notes that the causal theory should commend itself strongly to theists. Traditional Christian theology has always affirmed that God causally sustains the universe in existence at every moment. So the most basic relationship in the universe, for the Christian, is already a causal relationship. The causal theory of time simply builds on this foundation and says: where there is causation, there is time.¹⁹

Which Theory Is Correct? And Why It Matters

Each of these three theories has strengths and weaknesses. The relational theory is elegant but circular. The substantival theory is robust but raises difficult questions about God's freedom and the Principle of Sufficient Reason. The causal theory is powerful but depends on a particular understanding of causation.

What matters most for our purposes is this: each theory leads to a different conclusion about God's relationship to time. If the relational theory is correct, and time only exists when there are events, then before creation there may have been no time — and God may have been timeless before He created the world (this is Craig's position, as we will see in Chapter 8). If the substantival theory is correct, and time is a real container that exists independently, then God could have existed in time eternally — there was never a moment when He was not in time. If the causal theory is correct, and time is grounded in causation, then the causal relations within the Trinity generate divine temporality even before creation — and God has always been temporal.

I lean toward a combination of the substantival and causal theories. I believe that time is a real feature of reality — not merely a way of describing relationships between events — and that it is fundamentally grounded in causation. This allows me to affirm, with Mullins and DeWeese, that God has always been temporal: the dynamic life of the Trinity generates temporality within God's own being, quite apart from the existence of any created universe. Created, physical, measurable time — the kind of time our clocks track — began at creation. But time itself, as a feature of the divine life, did not begin. It has always been there, because the Trinity has always been there.

But this is getting ahead of ourselves. We need to introduce an even more important distinction — one that has dominated the philosophy of time for the last century and has enormous implications for theology.

The Most Important Distinction: The A-Theory vs. the B-Theory of Time

If you remember only one thing from this chapter, let it be this: the most important distinction in the entire philosophy of time is between the A-theory and the B-theory of time. These two theories offer radically different pictures of what time is like, and the one you accept will profoundly shape your understanding of God.

The names "A-theory" and "B-theory" come from the British philosopher J.M.E. McTaggart, who proposed them in 1908 in a famous argument about whether time is even real.²⁰ As Mullins notes, McTaggart "gave them the most creative names in the history of philosophy: the A- and B-theories of time."²¹ The names are not exactly inspiring — they sound more like battery sizes than grand philosophical theories. But the ideas behind them are profoundly important.

The A-Theory: Time Really Flows

The A-theory of time (also called the "dynamic" or "tensed" theory) says that time genuinely flows. The present moment is real and special. The past is gone — it has already happened and no longer exists (at least not in the same way). The future has not yet arrived — it does not yet exist (at least not in the same way). Temporal becoming is a real feature of reality: things really do come into existence and pass out of existence. The "now" is not an illusion. It is the cutting edge of reality.

Here is an analogy. Think of watching a movie in a theater. Each scene comes, plays out before your eyes, and then passes away. The current scene — the one on the screen right now — is the "present." The scenes that have already played are "past." They happened, but they are no longer happening. The scenes that have not yet played are "future." They will happen, but they have not happened yet. On the A-theory, reality is like this movie: it unfolds, moment by moment, with the present always moving forward.

As Craig explains, the A-theory holds that events can be described in terms of having the properties of being past, present, or future. These properties change over time. An event that is now in the future will eventually become present, and then pass into the past. This change — this "flow" from future to present to past — is real. It is not an illusion. It is a genuine feature of the way the world works.²²

On the A-theory, the present moment has a special status. It is objectively real in a way that the past and future are not (or at least not in the same way). The past is fixed — it really happened, and nothing can change it. The future is open — it has not yet been decided, and it is not yet actual. The present is where the action is. It is the locus of experience, of decision, of agency.

The B-Theory: All Moments Are Equally Real

The B-theory of time (also called the "static" or "tenseless" theory) tells a very different story. On this view, all moments of time are equally real. The past is just as real as the present. The future is just as real as the past. There is no objective "flow" of time. The appearance of time "passing" is an illusion — or at best a feature of our human consciousness, not a feature of reality itself.

Think of it this way. Instead of watching a movie in the theater, imagine taking the entire film reel and laying it out on a table. You can see all the frames at once — the beginning, the middle, and the end. No frame is more "real" or "special" than any other. They are all equally there. The impression that the movie is "moving" only arises when you run the film through a projector. But the film itself does not move. All the frames simply exist, side by side, in a static block.

This is exactly how the B-theory sees the universe. The universe is like a four-dimensional "block" — three dimensions of space and one dimension of time — where all events, past, present, and future, exist together. Philosophers call this the "block universe." In the block universe, the birth of Jesus and the end of the world are equally real. They differ only in their location within the block — one is "earlier" and the other is "later" — but neither is more real than the other.²³

On the B-theory, the only relationships between events are the relations of "earlier than," "later than," and "simultaneous with." These are permanent, unchanging relationships. The Battle of Waterloo is always earlier than the moon landing, and the moon landing is always later than the Battle of Waterloo. These relationships never change. There is no flow. There is no "now" that moves forward through time. The impression that the present is special — that we are living at the "cutting edge" of time — is just a quirk of human consciousness. Reality itself is static and tenseless.

Why This Matters Enormously for Theology

The A-theory/B-theory distinction is not just an abstract philosophical puzzle. It has direct and enormous implications for how we understand God. Let me explain why.

If the B-theory is true, divine timelessness becomes much more natural and intuitive. If all moments of time are equally real — if the universe is a static block — then it makes sense to think of God as existing "outside" the block, viewing all of it at once from a timeless perspective. God sees the birth of Abraham and the return of Christ with equal clarity, because both are equally real in the block. God does not need to wait for the future to arrive, because the future is already there. This picture fits very comfortably with the classical doctrine of divine timelessness.

If the A-theory is true, divine temporality becomes much more natural and intuitive. If only the present is real — if the past has passed away and the future has not yet arrived — then God exists in a genuine present. He acts in a real "now." He responds to events as they happen. He hears prayers in real time. He grieves over suffering as it occurs. The picture of God that emerges from the A-theory is a God who is actively engaged in the present moment — not a God who stands outside of time viewing a static block.

As Craig has argued at length, the A-theory of time is more congenial to theism and to the biblical portrait of God than the B-theory. The Bible overwhelmingly presents God as acting in time — creating, speaking, calling, judging, saving, responding, and entering into real-time relationships with His creatures. This portrait makes far better sense on the A-theory, where the present is real and temporal becoming is genuine, than on the B-theory, where all of history is a frozen block.²⁴

DeWeese agrees. After developing his causal theory of dynamic time, he observes that the A-theory, with its genuine temporal flow, provides the most natural framework for understanding God's temporal life. The God of the Bible is a God who acts — and genuine action requires a genuine present in which to act.²⁵

I should note, however, that the relationship between the A-theory/B-theory distinction and the God-and-time question is not perfectly simple. As Mullins points out, many writers have assumed that if the B-theory is true, God must be timeless, and if the A-theory is true, God must be temporal. But this is not quite right. It is logically possible to hold the B-theory and still affirm divine temporality (perhaps God moves through the block), and it is logically possible to hold the A-theory and still affirm divine timelessness (perhaps God transcends the dynamic flow). Nevertheless, there is a strong natural fit between the A-theory and divine temporality, and between the B-theory and divine timelessness. The connections are not airtight, but they are powerful.²⁶

I believe the A-theory is correct. Time genuinely flows. The present is objectively real. Temporal becoming is a real feature of reality. As we will see in Chapter 24, where we give the full philosophical treatment of this debate, I think the A-theory is more philosophically defensible and more compatible with the biblical portrait of God than the B-theory. For now, I simply want to plant the flag: the A-theory vs. B-theory distinction matters enormously, and the position we take on it will shape everything else in this book.

Three Ontologies of Time: Presentism, the Growing Block, and Eternalism

Closely connected to the A-theory/B-theory distinction are three different views about what moments of time actually exist. Philosophers call these views "ontologies of time" — theories about the being or reality of time. Understanding them will help us see more clearly what is at stake in the God-and-time debate.

Presentism: Only the Present Exists

Presentism is the view that only the present moment exists. The past no longer exists — it has passed away. The future does not yet exist — it has not arrived. Only the present is real. As the philosopher Trenton Merricks puts it, "an object has only those properties it has at the present time. The difference between past, present, and future is metaphysical, not perspectival."²⁷

On presentism, things endure through time by existing as a whole at each present moment. An object does not have "parts" scattered across past, present, and future. It exists entirely in the present. As time passes, the present moment gives way to a new present moment. What was present becomes past (and ceases to exist), and what was future becomes present (and comes into existence). Temporal becoming — the coming-to-be and passing-away of things — is absolutely real.²⁸

Presentism is the ontology of time most naturally associated with the A-theory. If time genuinely flows and the present is special, it makes sense to say that only the present is real. Presentism also has important implications for the God-and-time debate. If only the present exists, and if God is timeless (existing outside of time altogether), then what exactly is God "seeing" when He looks at the past or the future? They do not exist. A timeless God cannot be simultaneously aware of all of history if most of history does not exist. This creates a serious problem for divine timelessness, as we will explore in later chapters.

The Growing Block: The Past and Present Exist, but the Future Does Not

The growing block theory (sometimes called the "growing universe" theory) says that both the past and the present are real, but the future is not. The universe is like a block that grows over time. New moments are added to the block as they become present, and they remain in the block as they pass into the past. But future moments have not yet been added — they do not exist.

Think of it as a book being written one page at a time. The pages that have already been written (the past) still exist — they are in the book. The page currently being written (the present) is real. But the pages that have not yet been written (the future) do not exist yet. The book is growing, one page at a time.

The growing block is an interesting middle position. It preserves the A-theory's emphasis on temporal becoming (new moments genuinely come into existence) while also affirming that the past is real (unlike presentism, which says the past has ceased to exist). Some A-theorists, like Michael Tooley and DeWeese, find this view attractive because it allows them to say that past events are genuinely real while maintaining that the future is open.²⁹

Eternalism: All Moments Are Equally Real

Eternalism is the view that all moments of time — past, present, and future — are equally real. This is the "block universe" view we described above. The universe is a four-dimensional block, and all events within it exist equally. The Battle of Hastings in 1066 is just as real as the moment you are reading this sentence. They differ only in their temporal location within the block.

Eternalism is the ontology of time most naturally associated with the B-theory. If there is no objective flow of time, and if all moments are equally real, then the universe is a static, eternal block. Eternalism is also widely (though not universally) thought to be implied by Einstein's theory of relativity, for reasons we will discuss shortly.

Eternalism is the ontology of time that most naturally supports divine timelessness. If all moments are equally real in a static block, then God can stand outside the block and view all of it at once — past, present, and future. There is no need for God to be "in" time, because time is just a dimension of the block, like width or height. God can see the entire block from His timeless perspective.

But eternalism has a cost. If the future is already real — if it already exists in the block — then there is a strong pull toward determinism. If tomorrow already exists just as much as today, then it seems like the future is already fixed. What room is there for genuine freedom? What room is there for God to respond to prayers, or for human beings to make real choices? These are questions we will explore in depth later in the book. For now, I simply note that the ontology of time we adopt — presentism, growing block, or eternalism — has direct implications for theology, and especially for the God-and-time question. (Chapter 24 provides the full philosophical treatment of these options.)

McTaggart's Paradox: The Argument That Time Is Not Real

Before we leave the A-theory/B-theory distinction, I want to briefly mention a famous philosophical argument that has shaped this entire debate. In 1908, the philosopher J.M.E. McTaggart published an argument that has become one of the most discussed in all of philosophy: the argument that time is unreal.³⁰

McTaggart's argument goes like this. He identifies two ways of describing events in time. The A-series describes events using the concepts of past, present, and future. The coronation of Queen Elizabeth is past. This sentence being read is present. Next Tuesday's sunrise is future. These properties change: what is now future will eventually become present, and then past. The B-series describes events using the relations "earlier than," "later than," and "simultaneous with." The coronation of Queen Elizabeth is earlier than the moon landing. The moon landing is later than the coronation. These relations never change.

McTaggart then argues that the A-series is essential to time — without the distinction between past, present, and future, there would be no time at all, only a static ordering. But he also argues that the A-series is contradictory. Every event must be past, present, and future — each event has all three properties. But having all three properties at once seems contradictory (an event cannot be both past and future at the same time). The natural response is to say that these properties are held at different times — an event is future first, then present, then past. But this response already assumes the A-series to explain the A-series, which is circular.³¹

McTaggart concluded that time is unreal — that it is an illusion of our consciousness. As Craig observes, virtually no philosopher has agreed with McTaggart's dramatic conclusion that time itself is unreal. But his argument has been enormously influential in shaping the debate about the nature of time. The question became: Is time tensed (A-theoretic) or tenseless (B-theoretic)?³²

I will not pursue McTaggart's argument in detail here — that is the work of Chapter 24, where we give the full philosophical treatment. But I mention it because it is the source of the A-theory/B-theory terminology that runs throughout this entire book, and because the debate over whether McTaggart's paradox succeeds is still very much alive. Scholars are sharply divided. Some think McTaggart uncovered a deep truth about time. Others think his argument is, in the words of one philosopher, "a glorified mistake."³³ I fall into the latter camp, and I believe the A-theory survives McTaggart's challenge — but this is a discussion for later.

A Brief Introduction to Einstein's Relativity and Time

No discussion of time would be complete without at least a brief look at what modern physics has to say. And in modern physics, the most important figure for the philosophy of time is Albert Einstein. His theories of relativity — the Special Theory of Relativity (1905) and the General Theory of Relativity (1915) — revolutionized our understanding of time and have had enormous implications for the A-theory/B-theory debate.

I want to be clear at the outset: we are going to keep this brief and accessible. Chapter 31 provides the full treatment of relativity and its theological implications. Here, I simply want to introduce the key ideas so that we have them in mind as we move through the rest of the book.

Time Dilation: Time Really Does Slow Down

One of the most remarkable predictions of Einstein's Special Theory of Relativity is that time does not pass at the same rate for everyone. It sounds like science fiction, but it has been confirmed by countless experiments: when an object moves very fast (close to the speed of light), time passes more slowly for that object relative to an object that is standing still.

This effect is called time dilation, and the most famous illustration of it is the Twin Paradox. Imagine two twins, Alice and Bob. Alice stays home on Earth while Bob gets into a spaceship and travels at nearly the speed of light to a distant star and back. When Bob returns, he finds that he has aged only a few years — but Alice has aged decades. Time literally passed more slowly for Bob because of his high-speed travel. This is not a thought experiment; real experiments with precise atomic clocks on airplanes and satellites have confirmed that time dilation is absolutely real.³⁴

Craig describes the Twin Paradox clearly: "one twin stays at home on earth while his brother goes on a high-speed journey into outer space and back. When they meet again, relativity theory predicts that the traveling twin will have lived through a shorter time and so be younger than his stay-at-home brother."³⁵ This is remarkable. Time is not the fixed, uniform flow that Newton imagined. It is flexible. It stretches and shrinks depending on how fast you are moving.

The Relativity of Simultaneity: No Universal "Now"

Even more important for the philosophy of time is another consequence of Special Relativity: the relativity of simultaneity. In everyday life, we assume that when something happens "now" for us, it is also happening "now" for everyone else. But Special Relativity tells us that this is not the case. Which events are simultaneous — which events are happening "at the same time" — depends on your state of motion. Two events that are simultaneous for one observer may not be simultaneous for another observer who is moving at a different speed.

This is deeply puzzling. If there is no universal "now" — no single present moment shared by everyone — then what happens to the A-theory's claim that the present is objectively real? If "the present" is different for different observers, how can it be objectively special?

As Deng explains, the A-theory "makes central use of the idea that the present is metaphysically privileged in some way." But in relativity theory, "it is not clear what can count as 'the present.'" What we mean by "the present" is something like reality as it is everywhere right now — a global "now." But relativity tells us that there is no such thing. Distant simultaneity no longer exists. As a result, the idea of a global now that has metaphysical significance "becomes hard to sustain."³⁶

The "Block Universe" Interpretation

Many physicists and philosophers have drawn a dramatic conclusion from the relativity of simultaneity: the universe must be a "block." If there is no objective present, then all moments of time must be equally real. Past, present, and future all exist together in a four-dimensional spacetime block (called Minkowski spacetime, after the mathematician Hermann Minkowski who first developed the idea). On this picture, the "flow" of time is an illusion. The universe simply is — a static, unchanging, four-dimensional object.

Craig notes that on the Minkowski spacetime interpretation, "three-dimensional objects do not exist!" Reality is four-dimensional, and what we perceive as three-dimensional objects are simply cross-sections of four-dimensional entities viewed from a particular angle. The apparent "distortion" of objects at high speeds (length contraction) is just a matter of looking at four-dimensional objects from different perspectives — like how a three-dimensional object looks foreshortened when viewed at an angle.³⁷

If the block universe interpretation is correct, then the B-theory of time wins — and divine timelessness becomes the more natural position. God can be outside the block, viewing all of it at once.

But the Block Universe Is Not the Only Option

Here is the crucial point that many people miss: the block universe is not the only way to interpret relativity. It is one interpretation, but there are others — and some of them are perfectly compatible with the A-theory of time.

Craig has argued at length for the neo-Lorentzian interpretation of relativity. Named after the Dutch physicist Hendrik Lorentz (who developed a version of relativity theory independently of Einstein), this interpretation preserves absolute simultaneity — a real, universal "now" — while still accounting for all the experimental predictions of Special Relativity. On the Lorentzian view, there does exist a privileged reference frame in which simultaneity is absolute. Time dilation and length contraction are real physical effects caused by motion relative to this privileged frame, not mere differences in perspective. Observers who are in motion will calculate different events to be simultaneous with themselves, but "the discrepancy exists only in their measurements, not in reality."³⁸

This is a crucial point. The Lorentzian interpretation is empirically equivalent to the standard interpretation — it makes all the same predictions, and no experiment can distinguish between them. Yet it preserves the reality of absolute time and a genuine present moment. As Craig writes, "A Lorentzian theory of relativity is wholly compatible with the reality of tense and temporal becoming, since these are characteristics of absolute time."³⁹

DeWeese makes a similar point. He notes that many announcements from scientists claiming that relativity has "proved" certain metaphysical conclusions should be treated with caution. After more than a century of working with relativity theory, physicists are still not agreed on the physical interpretation of the theory's mathematical elements. "Consequently, announcements of scientists to the effect that certain metaphysical or physical points have been proved by relativity theory should not be taken as conclusive arguments."⁴⁰

Furthermore, as Mullins observes in God, Time, and the Incarnation, what Einstein demonstrated was not necessarily that absolute time does not exist, but rather "that it is not physically detectible." Newton would hardly have been impressed by this, since he never claimed that absolute time was physically detectable in the first place — he always considered it to be metaphysical in nature.⁴¹

Light-Clocks, Thought Experiments, and What They Show Us

Let me offer one more illustration to help us understand time dilation, because it is genuinely remarkable and worth grasping clearly. Physicists use a thought experiment called the light-clock to illustrate how Special Relativity works.

Imagine a simple clock that consists of two mirrors facing each other, with a beam of light bouncing back and forth between them. Each time the light bounces off a mirror, the clock "ticks." If the mirrors are standing still, the light travels straight up and down between them. The distance is short, and the clock ticks quickly.

Now imagine the same light-clock moving sideways at a high speed. From the perspective of someone watching the clock go by, the light beam is no longer traveling straight up and down. Instead, it is traveling in a diagonal zigzag pattern — because the mirrors are moving sideways while the light bounces between them. The diagonal path is longer than the straight up-and-down path. Since the speed of light is always the same (this is Einstein's key postulate), and since the light has to travel a longer path, each "tick" of the clock takes longer. The moving clock literally runs slower than the stationary clock.

This is not a trick of perspective. The moving clock really does tick more slowly. Time genuinely passes more slowly for the moving clock. And since anything that moves can be thought of as carrying its own "clock" (because all physical processes — chemical reactions, biological aging, the ticking of watches — are governed by the same physical laws), time dilation affects everything. The moving twin in our earlier thought experiment really does age more slowly.

Why does this matter for theology? Because it shows us that time — at least physical, measurable time — is far more flexible and strange than our everyday experience suggests. Time is not the rigid, uniform flow that Newton imagined. It bends, stretches, and warps. And if physical time is this flexible, then perhaps we should not be too quick to assume that God's experience of time must be identical to ours. Perhaps God's temporal experience is qualitatively different from creaturely time — not the rigid, uniform, clock-driven time we experience, but something richer and more flexible. As I argue in this book, God genuinely experiences temporal succession, but He is not bound by created, physical time. He has access to all of time — past, present, and future — through a unique divine capacity that transcends our temporal limitations. The flexibility of time revealed by relativity at least opens the door to this possibility.

Metaphysical Time vs. Physical Time: A Crucial Distinction

One of the most important distinctions for our project — and one that is often overlooked in popular discussions — is the distinction between metaphysical time and physical time. Craig draws this distinction clearly, and getting it right will save us from many confusions.

Physical time is the time measured by clocks, governed by the laws of physics, and affected by things like gravity and velocity. It is the time studied by physicists. It is the time that dilates near the speed of light and warps near massive objects. Physical time began with the Big Bang (or, more precisely, with whatever physical event initiated our universe).

Metaphysical time (sometimes called "ontological time" or "real time") is something deeper. It is the fundamental temporal structure of reality — the genuine sequence of before and after that underlies all events. Metaphysical time is A-theoretic: it involves real temporal flow, real becoming, and a real distinction between past, present, and future. Unlike physical time, metaphysical time is not affected by velocity or gravity. It is not the kind of thing that clocks measure.⁴²

This distinction is crucial because many arguments about God and time conflate the two. When someone says "there was no time before the Big Bang," they are talking about physical time — the time measured by clocks and governed by the laws of physics. But it does not follow that there was no metaphysical time before the Big Bang. If God existed before creation, and if God's inner life involved genuine sequence (the Father loving the Son, deliberating, deciding to create), then there was a form of time — metaphysical time, divine time — even before physical time began.

Mullins makes a related point in The End of the Timeless God. He argues that we need to distinguish between different senses of "time." Physical time is a feature of the created universe. But time in the broader sense — genuine sequence and succession — may be a feature of God's own being. If the A-theory is correct, then metaphysical time is more fundamental than physical time. Physical time is a particular instance of metaphysical time — the instance that began with creation and is governed by the laws of physics. But metaphysical time itself may be eternal.⁴³

Craig follows in what he calls "the classical Newtonian tradition of positing absolute time," though he understands this time as metaphysical, not physical. The time God experiences is not the time that clocks measure. It is deeper and more fundamental. Craig writes that the time experienced by God is "metaphysical, or ontological, or real time, not to be identified with physical time." He adds that "the failure to distinguish metaphysical time from physical time is the root of many misapplications" of relativity theory to the God-and-time debate.⁴⁴

I agree with Craig on this point, even though I disagree with him on other aspects of the God-and-time question (particularly his claim that God was timeless before creation, which we will examine in Chapter 8). The distinction between metaphysical and physical time is essential. When we ask whether God is "in time," we are not asking whether God is subject to the ticking of atomic clocks or the time dilation of Special Relativity. We are asking whether God's experience involves genuine sequence — whether there is a real "before" and "after" in God's life. That is a metaphysical question, not a physics question.

The Direction and Flow of Time: Why Does Time Move Forward?

Before we close this chapter, I want to touch on one more fascinating aspect of time: its direction. We all know from experience that time moves in one direction — forward. We remember the past but not the future. We can influence the future but not the past. Eggs break but do not unbreak. People grow old but do not grow young. This one-directional character of time is so fundamental to our experience that we rarely stop to ask: Why? Why does time move forward and not backward?

This question — often called the problem of "time's arrow" — has puzzled philosophers and physicists for centuries. The laws of physics (with a few minor exceptions) are "time-symmetric" — they work equally well in either direction. If you filmed a ball bouncing and played the film backward, the physics would look perfectly normal. So why does time always run in one direction?

The causal theory of time, which we discussed earlier, offers a particularly satisfying answer. DeWeese argues that causation explains both the flow and the direction of time. Causes come before their effects — always. This asymmetry in causation gives time its direction. Time flows from cause to effect, from earlier to later, because causation flows that way. And time flows — rather than standing still — because new causes are constantly producing new effects, pushing the present forward into the future.⁴⁵

The B-theorist, by contrast, has a much harder time explaining why time seems to flow in one direction. If all moments are equally real, and if there is no genuine "flow," then the apparent direction of time is just a feature of our psychology — not a feature of reality. Many people find this deeply unsatisfying. Our experience of temporal direction — the feeling that the past is behind us and the future is ahead — is so vivid and universal that dismissing it as an illusion seems like an extraordinary claim.

For theology, the direction of time matters because the Bible presents God's action as purposeful and directional. God is moving history toward a goal — the redemption and restoration of all things. Salvation history unfolds from creation to fall to redemption to consummation. This grand narrative only makes sense if time is genuinely directional — if it really is going somewhere. A block universe, in which all moments simply exist side by side with no real flow or direction, seems to undermine the very idea of a purposeful divine plan that unfolds over time.

What Does This Mean for Theology? Some Preliminary Observations

We have covered a lot of ground in this chapter. Let me draw together some preliminary observations about why all of this matters for our central question: What is God's relationship to time?

First, the theory of time we adopt — relational, substantival, or causal — will shape our answer to the question of whether God was temporal before creation. If time is relational and depends on events, then before creation there may have been no time, and God may have been timeless (Craig's view). If time is substantival or grounded in causation, then God may have been temporal even before creation, because time (or causation) was already a feature of His own being (Mullins's and DeWeese's view). I believe the causal theory is the most promising, and I agree with Mullins that the intra-Trinitarian relations generate a form of divine temporality even apart from creation.

Second, the A-theory/B-theory distinction has enormous theological implications. The A-theory — with its genuine present, real temporal flow, and open future — provides the most natural philosophical framework for the biblical portrait of a God who acts in time, responds to prayer, grieves over sin, and enters into real-time relationships with His creatures. The B-theory — with its static block universe and denial of temporal flow — provides a more natural framework for divine timelessness. I believe the A-theory is correct, and I will argue this case in detail in Chapter 24.

Third, Einstein's relativity, while a stunning achievement of modern physics, does not settle the theological question. The block universe is one interpretation of relativity, but not the only one. The neo-Lorentzian interpretation preserves absolute time and temporal becoming while making all the same experimental predictions. Physics does not require us to give up the A-theory. The full treatment of this issue will come in Chapter 31.

Fourth, the distinction between metaphysical time and physical time is crucial. When we ask whether God is "in time," we are not asking whether God is subject to clocks, time dilation, or the laws of Special Relativity. We are asking whether God's experience involves genuine sequence — whether there is a real "before" and "after" in God's life. Physical time began with the Big Bang. But metaphysical time — the genuine sequence of before and after — may be a feature of God's own eternal being.

Fifth, and finally, I want to close with a conviction that will run throughout this book: theology should drive philosophy, not the other way around. If the Bible clearly presents God as acting in time, responding to events, and entering history at particular moments — and I believe it does, overwhelmingly — then our philosophical framework needs to accommodate that biblical portrait. We should not let a philosophical theory (whether the B-theory, eternalism, or a particular interpretation of relativity) force us to reinterpret the clear teaching of Scripture. Philosophy and science are valuable tools for understanding God and the world, and we should engage them with rigor and honesty. But when philosophy or science appears to conflict with the plain teaching of the Bible, we should hold our philosophical conclusions loosely and our biblical convictions firmly.

This is not anti-intellectualism. It is a matter of priorities. As Craig himself has written, his philosophical works on time are ultimately in service of the theological question: What is God's relationship to time?⁴⁶ The philosophy of time is fascinating in its own right, but for us — as Christians seeking to understand the living God — it matters because it helps us understand the One who made time, who enters time, and who will one day bring time to its glorious fulfillment.

This conviction connects directly to the arguments we develop in the companion volumes to this book. In The Heart of God, we argue that God has genuine emotional responses to His creatures — real love, real grief, real joy. But genuine emotional response requires temporal sequence: something happens, and then God responds to it. A timeless God cannot respond, because response requires a "before" (the event) and an "after" (the response). The philosophy of time we adopt must be able to account for a God who genuinely responds — and the A-theory, with its real flow and genuine present, provides exactly that framework. Similarly, in The Word Made Flesh, we argue that God the Son entered human history — He was born at a particular moment, grew over time, suffered and died on a particular afternoon. The Incarnation is an event that happens in time. If we adopt a philosophy of time that rules out genuine temporal becoming, we make the Incarnation philosophically incoherent. The stakes of the philosophy of time for theology could hardly be higher.

In the next chapter, we will turn from philosophy to the Bible itself. We will examine the biblical language of time and eternity — the Hebrew word olam (עוֹלָם) and the Greek word aiōn (αἰών) — and ask what the biblical writers actually meant when they called God "eternal." The answer, as we will see, is surprising — and it has been widely misunderstood for centuries.