Chapter 1

Introduction — Why the Incarnation Demands We Get Human Nature Right

Part I: Foundations — What Is a Human Being?

The Most Staggering Claim Ever Made

Picture a baby. A tiny, wrinkled newborn, eyes barely open, fists clenched, crying for His mother's milk. Now imagine someone telling you that this child — this helpless infant lying in a feeding trough in a dusty Judean village — is the eternal God. The One who spoke the galaxies into being. The One who set the stars in their courses and holds every atom together by the word of His power. This baby is that God. Not a symbol of God. Not a representative of God. Not someone especially close to God. This child is God — truly, fully, completely.

That is the doctrine of the Incarnation. And it is, without any exaggeration, the most extraordinary claim in all of human thought.

The word "incarnation" comes from the Latin incarnatio, which simply means "becoming flesh" or "taking on a body." It refers to the Christian belief that the second Person of the Trinity — God the Son, the eternal Word — took on a genuine human nature and became the man Jesus of Nazareth, while never ceasing to be fully God. The apostle John put it in the simplest and most breathtaking way possible: "The Word became flesh and dwelt among us" (John 1:14, ESV).¹

Think about what that sentence actually claims. The infinite became finite. The eternal entered time. The all-powerful became a helpless infant. The One who sustains all life became dependent on a teenage mother for food. The Creator of the human body took on a human body. The Maker of every human soul took on a human soul.

We are so accustomed to hearing this claim in church — so familiar with the Christmas story, so comfortable with the carols — that we can forget how shocking it truly is. No other religion in the history of the world has ever made a claim quite like this one. Other ancient religions have stories of gods appearing in human form, but those are temporary disguises — like an actor putting on a costume and then taking it off when the show is over. The Christian claim is radically different. We are not saying that God pretended to be human. We are not saying He wore a human body like a mask. We are saying that the eternal Son of God became a real human being — that He took on a genuine human nature, with a real human body and a real human soul, and that He remains human forever. This is not a costume. It is a permanent union.

The early Christians were so overwhelmed by this truth that they called it the "great mystery of godliness." The apostle Paul wrote: "Great indeed, we confess, is the mystery of godliness: He was manifested in the flesh" (1 Tim 3:16, ESV). The word "mystery" here does not mean something unknowable or irrational. It means something so vast, so deep, and so wonderful that we will spend eternity exploring it and never reach the bottom. The Incarnation is not an intellectual puzzle to be solved and filed away. It is an ocean of wonder to be entered and explored.

But here is where things get complicated. As wonderful as the Incarnation is, it raises profound questions. How can one Person be both infinite and finite? How can the same individual be both omniscient (all-knowing) and yet genuinely grow in wisdom (Luke 2:52)? How can the Son of God be both omnipotent (all-powerful) and genuinely weak — hungry, tired, thirsty, vulnerable to suffering and death? How can God die? These questions have occupied the greatest minds in Christian history for two thousand years. And while we will never fully comprehend the mystery, the church has discovered that careful thinking about the Incarnation — guided by Scripture, the creeds, and the ecumenical councils — can bring us to a deep and satisfying understanding of how these truths fit together.³⁰

Either this is the most glorious truth in the universe — the moment when God Himself bridged the infinite gap between Creator and creature, entering our world from the inside in order to save us — or it is the most spectacular incoherence ever proposed. Everything hangs on whether we can make sense of it. And as I hope to show in this book, making sense of the Incarnation requires that we first answer a question that might seem unrelated but turns out to be absolutely essential: What is a human being?

The Question That Changes Everything

What is a human being? At first glance, that might seem like a question for a biology textbook or a philosophy classroom. What does it have to do with who Jesus is?

The answer: everything.

Think about it this way. If I tell you that a master sculptor took a block of marble and turned it into a masterpiece, you need to know what marble is to appreciate what happened. If I tell you that a brilliant chef took simple ingredients and created an unforgettable meal, you need to know what the ingredients are to understand the achievement. In the same way, when the Bible tells us that God the Son "became human," we need to know what "human" means to understand the Incarnation. The ingredients matter. The raw materials matter. What the Son took on — what He became — determines what the Incarnation actually is.

When Christians say that God the Son "became human," we need to know what "human" means. What exactly did the Son take on? What did He become? If we get this question wrong, we get the Incarnation wrong. And if we get the Incarnation wrong, we get Jesus wrong. And if we get Jesus wrong, we get everything wrong — the cross, the resurrection, salvation itself.

The question "What is a human being?" might seem like it has an obvious answer. A human being is a person with a body — someone with arms, legs, a brain, a heart. And that is partly right. But the deeper question is this: Is a human being only a physical body? Or is there something more — something invisible, something immaterial, something we might call a "soul" or a "spirit" that is just as real and just as essential as the body?

Today, two very different answers compete for our attention. One answer is called physicalism (sometimes called "materialism" or "monism"). Physicalism says that a human being is entirely physical. There is no immaterial soul. What we call "the mind" or "consciousness" is just the activity of the brain. When the brain stops working, the person ceases to exist — unless God steps in and re-creates them at the resurrection. On this view, you are your body. There is nothing else to you.²

The other answer is called substance dualism. Dualism says that a human being is made up of two distinct things: a physical body and an immaterial soul. The body is the material part you can see and touch. The soul is the immaterial part — the seat of your consciousness, your thoughts, your will, your identity. Body and soul are deeply connected in life, but they are not the same thing. When the body dies, the soul continues to exist. It survives death. It remains conscious and aware.³

Now, you might be wondering: Why does this matter for understanding Jesus? The answer is simple, and it is the driving force behind this entire book. If physicalism is true — if human beings are nothing more than physical organisms — then Jesus Christ has no immaterial human soul. His "human nature" is just His body. And that creates a set of devastating problems for the most central doctrines of the Christian faith.

This is not an obscure debate among ivory-tower academics. Over the past few decades, a growing number of Christian philosophers and theologians have embraced some form of physicalism. They have done so for a variety of reasons — because they believe modern neuroscience has made the soul unnecessary, because they think the Bible teaches a holistic view of human nature that does not include an immaterial soul, or because they find the philosophical problems with dualism (such as the so-called "interaction problem" — how does an immaterial soul interact with a material body?) too severe. Some of the most respected scholars in evangelical and mainline Christianity have argued for physicalism, including Nancey Murphy, Joel Green, Kevin Corcoran, and others. Their work is thoughtful and their intentions are good.

But here is what concerns me. Most of the discussion about physicalism and dualism has focused on philosophy of mind, neuroscience, and biblical anthropology. Very few scholars have asked the question that I believe is the most important one of all: What does physicalism do to the Incarnation? If we accept that humans are purely physical — that there is no immaterial soul — what happens when we apply that same view to Christ? What happens to the union of His two natures? What happens at the cross? What happens during the three days in the tomb? What happens at the resurrection? What happens to the permanent incarnation — the reality that Christ is still God and man right now?

When we ask those questions, I believe, the results are devastating. Physicalism does not merely create minor difficulties for Christology. It creates catastrophic ones. It threatens to unravel the very heart of the Christian faith. And that is why I have written this book.

What Went Wrong at the Cross? A Thought Experiment

To see why the question of human nature matters so much for Christology — the study of who Jesus is — let me walk you through a thought experiment. Imagine you are standing at the foot of the cross on Good Friday. You watch as Jesus suffers, speaks His final words, and then breathes His last. He dies.

Now ask yourself: What just happened?

If substance dualism is true, then here is what happened: Jesus' body died, but His soul — His immaterial human soul — survived. It separated from His body, just as any human soul separates from its body at death. But here is what makes this so important: the eternal Son of God was still united to that soul. The Incarnation did not end. The Son remained incarnate — still united to a human nature (specifically, His human soul) — even while His body lay dead in the tomb. His soul was active. He descended to the place of the dead. He proclaimed victory. He was "put to death in the flesh but made alive in the spirit," as the apostle Peter writes (1 Pet 3:18, ESV). The Incarnation survived Good Friday.⁴

But if physicalism is true, then something very different happened. If a human being is nothing but a physical body, then when Jesus' body died, His entire human nature ceased to function. There was no soul to survive. There was nothing human left for the Son of God to be united to. The Son was no longer incarnate. The Incarnation was over. For three days — from Good Friday to Easter Sunday — God the Son was not "God and man." He was just God.

Do you see the problem? The great ecumenical councils of the church — especially the Council of Chalcedon in AD 451 — declared that Christ's two natures are united "without separation."⁵ The divine nature and the human nature can never come apart. But if physicalism is true, they did come apart at the cross. The human nature was destroyed. The Incarnation was interrupted. And that is a catastrophe for orthodox Christianity.

This period between Jesus' death on Friday and His resurrection on Sunday is called the triduum mortis — a Latin phrase that simply means "the three days of death." It is the most critical test case for any theory of human nature applied to Christ. What happened during the triduum? Was Christ still incarnate? Was His human nature still intact? Was the Son of God still united to something human? These questions will be examined in detail in Chapters 21 and 22, but the basic problem should already be clear: physicalism cannot explain how the Incarnation survived the cross.

Seven Problems Physicalism Creates for the Incarnation

The triduum mortis is only one of the problems. Let me briefly preview seven ways that physicalism about human nature creates devastating difficulties for orthodox Christology. Each of these will be developed at length in later chapters, but this overview will give you a sense of how far-reaching the problem is.

First, the hypostatic union is destroyed at the cross. The "hypostatic union" is a technical term for the union of Christ's two natures — divine and human — in one Person. The word hypostasis (ὑπόστασις) is Greek for "person" or "individual reality." The hypostatic union is the heart of Chalcedonian Christology: one Person, two natures, united forever. But on physicalism, when Jesus died, His human nature (which is His physical body, on the physicalist view) ceased to function. There was no soul to maintain the union. The hypostatic union was dissolved. The two natures came apart. This directly contradicts Chalcedon.⁶

Second, Jesus ceased to be God and man. If there is no soul to survive death, then between Good Friday and Easter Sunday, the Son of God was not incarnate. He existed as God — He is, after all, eternally divine — but He was no longer united to anything human. He was no longer "true God and true man," as the creeds confess. This is not a minor detail. This means the Incarnation was temporary, that it had a gap, that God's union with humanity was interrupted by death. As we will see in Chapter 22, this has devastating consequences.

Third, the descent to the dead becomes impossible. Both Scripture and the early creeds teach that Christ descended to the dead during the triduum. The Apostles' Creed says, "He descended into hell" (or "to the dead"). The apostle Peter writes that Christ "went and proclaimed to the spirits in prison" (1 Pet 3:19, ESV) and that "the gospel was preached even to those who are dead" (1 Pet 4:6, ESV). Paul says Christ "descended into the lower regions of the earth" (Eph 4:9, ESV). But on physicalism, there is no Christ to descend anywhere. His body was in the tomb. There was no soul. There was no person active between death and resurrection. The descent clause of the creed is emptied of meaning. This will be explored fully in Chapter 23.⁷

Fourth, the resurrection creates a fatal personal identity problem. On physicalism, if Jesus ceased to exist at death and was then "re-created" at the resurrection, is the risen Jesus the same Jesus who died? Or is He a copy — a replica who looks like Jesus, talks like Jesus, and has Jesus' memories, but is not actually the same person? This is a well-known problem in the philosophy of personal identity, and physicalism has no good answer. On dualism, the problem does not arise: the soul — which is the bearer of personal identity — survived death and was reunited with the glorified body. It is the same person because it is the same soul. Chapter 24 will address this in detail.⁸

Fifth, the permanent incarnation is undermined. Christ ascended bodily into heaven and remains incarnate forever. He is still God and man, right now, at the right hand of the Father. As 1 Timothy 2:5 says, "There is one mediator between God and men, the man Christ Jesus" — present tense. On dualism, this is coherent: Christ's human soul remains united to both His divine nature and His glorified body, providing a stable basis for the ongoing Incarnation. On physicalism, Christ's "human nature" is entirely constituted by His physical body. What does it mean for a purely physical human organism to be "seated at the right hand of the Father"? We will address this in Chapter 26.⁹

Sixth, Christ's sinlessness becomes inexplicable. On physicalism, sin and moral dispositions are entirely functions of physical brain states. If Christ had a normal human brain, how did He avoid sin? If His brain was physically different from ours — wired in some special way to prevent sin — then He did not truly share our human nature. And if He did not share our human nature, He cannot save us. On dualism, Christ's human soul — created sinless and sustained by the Holy Spirit — provides a coherent account of His sinlessness. Chapter 27 will develop this argument.¹⁰

Seventh, physicalism revives the ancient heresy of Apollinarianism. In the fourth century, a bishop named Apollinarius of Laodicea taught that Christ did not have a human rational soul. Instead, the divine Logos (Word) took the place of the human soul. The church condemned this teaching at the Council of Constantinople in AD 381, and again at the Council of Constantinople II in AD 553. Why? Because a Christ without a human soul does not have a complete human nature. And if He does not have a complete human nature, He cannot redeem our complete human nature. As Gregory of Nazianzus famously said: "What is not assumed is not healed."¹¹ Physicalism, by denying the existence of the soul altogether, effectively denies that Christ has what the councils insisted He must have. Although physicalists do not intend to be Apollinarian, the structural logic of their position produces the same result. This connection will be explored in depth in Chapter 12.

The Positive Case: How Substance Dualism Preserves the Incarnation

If physicalism creates all these problems, does dualism solve them? I believe it does — beautifully and completely.

On substance dualism, Christ's human nature consists of two components: a human body and an immaterial human soul. When Christ died on the cross, His body died — but His soul survived. The soul separated from the body, just as any human soul does at death. But the crucial point is this: the Son of God remained united to Christ's human soul during the triduum. The Incarnation was not interrupted. The hypostatic union was not dissolved. The two natures — divine and human — remained joined "without separation," exactly as Chalcedon teaches.

Let me walk through this step by step, because it is worth seeing how clean and elegant the dualist picture is at every stage of the story.

At the Incarnation itself, the Son of God assumed a complete human nature — a body and a soul. This was not a partial assumption. He did not take on a body alone and leave out the soul (that would be Apollinarianism). He did not take on a soul alone and leave out the body (that would be docetism — the heresy that Christ only appeared to have a physical body). He assumed both. The result was a complete, genuine human being — with all the capacities of human life, including physical sensation, emotion, rational thought, moral willing, and conscious experience. This complete human nature was united to the divine nature in one Person — the Son — forming the hypostatic union.

During His earthly life, Christ's body and soul functioned together in the normal way, just as yours and mine do. His soul animated His body. His thoughts, emotions, and decisions — the activity of His human soul — were expressed through His body. He walked, talked, ate, drank, wept, laughed, prayed, and taught. He experienced hunger, fatigue, pain, sorrow, joy, and love. All of this was the integrated activity of a genuine body-soul human being. And all of it was the activity of the Son of God, living a genuinely human life.

At the cross, Christ's body died. His soul separated from His body, just as happens at any human death. But — and this is the critical point — the Incarnation did not end. The Son of God remained united to Christ's human soul. He also remained united to Christ's body, even though the body was now dead and lying in the tomb. Thomas Aquinas made exactly this point in the thirteenth century: during the triduum, the divine nature remained united to both the separated soul and the dead body, though the soul and body were temporarily separated from each other. The Incarnation continued in a modified form — the Son was united to a human soul (in the place of the dead) and to a human body (in the tomb) — but the union of divine and human was never broken.

During the three days between death and resurrection, Christ's soul was active. He descended to the place of the dead, just as the creed says. He proclaimed victory to the spirits in prison, just as Peter says. He was with the penitent thief in paradise, just as He promised: "Today you will be with me in paradise" (Luke 23:43, ESV). None of this is possible without a soul. On physicalism, there is simply no Christ to do any of these things between Friday and Sunday. The body is in the tomb. There is no soul. There is no person. There is nothing.

At the resurrection, Christ's soul was reunited with His body — now glorified, transformed, and fitted for eternal life. Personal identity was perfectly preserved because the same soul that had inhabited the earthly body now inhabited the risen body. It was the same Jesus. Not a copy. Not a replica. The same Person, with the same soul, now in a new and glorious body. The risen Jesus could eat fish (Luke 24:42–43), could be touched (John 20:27), could walk and talk — but He could also pass through locked doors (John 20:19) and appear and disappear at will (Luke 24:31). His body was transformed, but His identity was continuous. The soul — the bearer of personal identity — guaranteed that continuity.

And at the ascension, Christ — body and soul, God and man — ascended to the right hand of the Father, where He remains forever. The Incarnation is permanent. The Son of God is eternally united to a human nature — a human body and a human soul — and will never cease to be the God-man. As the author of Hebrews says, "He holds his priesthood permanently, because he continues forever" (Heb 7:24, ESV). Right now, at this very moment, there is a human being at the right hand of God — a human being with a body and a soul — who is interceding for us. That is the permanent incarnation. And it only makes sense on dualism.

Substance dualism preserves every element of orthodox Christology. It holds the whole thing together. And that, I believe, is not a coincidence. The church has always taught that Christ has a human soul because the church has always understood that without a human soul, the Incarnation falls apart.

Christology Should Shape Our Anthropology

At this point, I want to introduce an idea that will be a key theme throughout this book. It comes from a recent and important work by Michael Wilkinson called Crowned with Glory and Honor: A Chalcedonian Anthropology. Wilkinson makes a powerful argument that our understanding of Christ should shape our understanding of human nature — not the other way around.¹²

Here is what I mean. The typical approach in the theological anthropology debate — the debate about what human beings are — is to start with philosophy or science, decide what a human being is (physical organism? body-soul composite?), and then apply that answer to Christ. So if the philosopher concludes that humans are purely physical, the theologian then tries to make the Incarnation work on physicalist terms. Christ becomes a purely physical human organism who is somehow also God.

Wilkinson says we should do the opposite. We should start with Christ. Christ is, as Wilkinson puts it, "the man par excellence" — the perfect, definitive human being.¹³ The ecumenical councils have told us what Christ's human nature consists of: a body and a rational soul. If Christ's human nature includes a soul, then human nature includes a soul. Christology norms anthropology. The doctrine of the Incarnation tells us what a human being is, not the other way around.

I find this approach deeply compelling, and it runs throughout the entire argument of this book. We do not first decide that humans are purely physical and then try to squeeze Christ into that mold. We look at what Christ is — true God and true man, with a divine nature and a complete human nature consisting of body and soul — and let that define what it means to be human. As Wilkinson argues, both dualist and physicalist models in contemporary anthropology work only at the nature level, focusing exclusively on the mind-body problem. But orthodox Christology uses a person-nature distinction that goes deeper — and if Christ, as the paradigmatic human, has this person-nature structure, then so should our understanding of humanity in general.¹⁴

This principle — Christology norms anthropology — will appear again and again in the chapters ahead. It will be developed most fully in Chapter 7, but it is one of the most important methodological commitments of this book.

The Landscape of the Debate: Orienting the Reader

Before we go further, it will help to orient the reader in the broader landscape of the debate about human nature. Joshua Farris, in his excellent An Introduction to Theological Anthropology, provides a helpful taxonomy of the major positions. Farris identifies several broad categories: reductive physicalism, nonreductive physicalism, the constitution view, emergentism, emergent dualism, hylomorphism (the Aristotelian-Thomistic view), and substance dualism.¹⁵ Each of these positions will be defined and explained in detail in Chapter 2. For now, it is enough to understand the basic lay of the land.

On one end of the spectrum is reductive physicalism, which says that mental states simply are brain states. There is nothing beyond the physical. Very few Christian thinkers hold this view, but it represents the logical endpoint of the physicalist trajectory.

More common among Christian scholars is nonreductive physicalism, championed by theologians like Nancey Murphy and biblical scholar Joel Green. Nonreductive physicalists say that mental properties are real and important — they cannot be reduced to simple chemistry — but they are still entirely produced by and dependent on the physical body. There is no immaterial soul. The "soul" is understood as a functional capacity of the body, not a separate thing.¹⁶

In the middle ground sits emergent dualism, developed by philosopher William Hasker. On Hasker's view, the soul genuinely emerges from the brain's complexity and becomes a real, distinct, immaterial substance — but its origin is physical. It arises from the body rather than being directly created by God. This is an interesting middle position that has some strengths but also creates unique Christological difficulties, as we will see in Chapter 25.¹⁷

There is also hylomorphism — the view associated with Aristotle and developed extensively by Thomas Aquinas. On this view, the soul is the "form" of the body — the organizing principle that makes the body a living human body. The soul can exist apart from the body after death, but its natural state is to be united with a body. This is not quite substance dualism in the traditional sense, but it does affirm a real, immaterial soul. Aquinas himself argued that Christ's soul survived the cross and maintained the hypostatic union during the triduum — which actually supports the argument of this book, even if the details of Aquinas's metaphysics differ from ours.¹⁸

And on the other end is substance dualism — the view I hold and the view this book defends. A human being consists of two distinct substances: a material body and an immaterial soul. The soul is directly created by God. It is the seat of consciousness, will, and personal identity. It can survive the death of the body and function apart from it. John Cooper calls this "holistic dualism" — body and soul are deeply integrated in life but ontologically distinct. They are two different kinds of things, even though they work together as a unified whole during earthly life.¹⁹

Farris helpfully frames his survey of these positions within a broader theological context, noting that how we answer the question of human nature has implications not just for philosophy but for Christology, the doctrine of sin, salvation, and the final hope of resurrection. What we believe about human nature touches everything else in the Christian faith.²⁰ That is precisely the conviction driving this book — and the Incarnation is where all these implications come to a head.

Wilkinson, for his part, notices something crucial that both sides of the dualism-physicalism debate tend to miss. Both dualists and physicalists work at the "nature level" alone — that is, they focus entirely on the relationship between body and mind (or body and soul). But orthodox Christology operates with a different framework: a person-nature distinction. In Christ, the Person (the divine Son) is not identical to the nature (human or divine). Wilkinson argues that this distinction should inform our anthropology as well — that a human being is not just a body-soul nature, but a person subsisting in a body-soul nature. This is what he calls a "Chalcedonian anthropology."²¹ While the full development of Wilkinson's model goes beyond the scope of this book, his key insight — that Christology should shape anthropology — is one that I embrace wholeheartedly.

The Author's Christological Position: A Brief Overview

Before previewing the book's structure, I should lay out the specific Christological position I hold. Each of these terms will be defined briefly here and developed in detail in later chapters.

Chalcedonian. I affirm the Christological definition of the Council of Chalcedon (AD 451): Jesus Christ is one Person (the eternal Son of God) who possesses two complete natures — a divine nature and a human nature — united in one hypostasis (person) "without confusion, without change, without division, without separation." This is the bedrock of orthodox Christology, and every position in this book is built on it.²²

Dyothelite. I affirm that Christ has two wills — a divine will and a human will. This was defined at the Third Council of Constantinople in AD 681. The two wills operate in harmony, with the human will freely submitting to the divine will. We see this clearly in Gethsemane, when Jesus prays: "Not my will, but yours, be done" (Luke 22:42, ESV). That prayer presupposes two distinct wills — one expressing the human will's natural recoil from suffering and one submitting to the Father's plan. The full treatment of dyothelitism appears in Chapter 14.²³

Kryptic (Loke's Divine Preconscious Model). I follow the Christological model developed by Andrew Ter Ern Loke, which he calls the "Kryptic Model" or the "Divine Preconscious Model." The key idea comes from the Greek word krypsis (κρύψις), which means "hiding" or "concealment." During the Incarnation, the Son of God did not give up (empty Himself of) His divine attributes — His omniscience, omnipotence, and omnipresence. That would be kenoticism, which I reject (see Chapter 15). Instead, these divine attributes were concealed — present at a "preconscious" level but not actively flooding Christ's waking human consciousness. Christ experienced a single, genuinely human stream of consciousness. He truly grew in wisdom. He truly did not know the day or hour of His return. But His divine knowledge and power were always there, operating "behind the scenes," available when the Father willed it — for miracles, for reading people's thoughts, for prophetic knowledge.²⁴

Think of it this way. You know your home address. Right now, as you read this sentence, you are probably not thinking about your address. That knowledge is "there" — stored in your memory, available if someone asks — but it is not at the forefront of your mind. In a very rough analogy, that is how Loke pictures the divine attributes during the Incarnation. They were present but concealed, accessible but not constantly in consciousness. This preserves both genuine humanity (Jesus truly experienced life with human limitations) and full deity (He never stopped being omniscient God). The full presentation and defense of this model appears in Chapter 17.

Concrete nature view. I hold that Christ's human nature is a concrete particular — a real, individual body-soul composite — not an abstract set of properties. The Son assumed a concrete human nature: a real human body united to a real human soul. This is important because it means the Incarnation involves a genuine, particular human being — not just an abstract quality called "humanity." The distinction between concrete and abstract nature views will be explored in Chapter 19.²⁵

I should also note my deep respect for the work of Timothy Pawl, whose In Defense of Conciliar Christology provides a rigorous philosophical defense of the ecumenical councils' Christological definitions. Pawl demonstrates that the councils' teaching is logically coherent — something many modern philosophers have doubted. While Loke's Kryptic Model is my preferred framework for explaining how the two natures relate in Christ's experience, Pawl's work is invaluable for defending the logical coherence of the conciliar framework itself. The full engagement with Pawl's work appears in Chapter 18.²⁶

This Book in Context: A Broader Theological Project

This book is the fourth in a series of interconnected theological studies, and it helps to understand how the pieces fit together. Each of these books addresses a different dimension of God's nature and His relationship to His creation, and together they form a unified vision of who God is, who we are, and how the Incarnation brings God and humanity together in the most intimate way imaginable.

The first book in the series, Beyond the Grave: A Biblical and Theological Case for Postmortem Salvation, laid much of the groundwork for the present study. That book argued for the conscious intermediate state — the view that the soul survives death and remains awake and aware between death and the final resurrection. It presented both the biblical and philosophical case for substance dualism, engaging extensively with the work of John Cooper, J. P. Moreland, and Richard Swinburne. It included detailed chapters on veridical near-death experiences (NDEs) — cases in which individuals who were clinically dead reported accurate observations of events they could not have known about through normal means — as empirical evidence for the existence of the soul. It also explored the relationship between dualism and physicalism within the conditional immortality movement, showing that many who hold to conditional immortality have unwittingly adopted a physicalist anthropology that creates serious theological problems. The present book builds on that foundation but goes much further. In Beyond the Grave, I showed that physicalism fails for human nature in general. Here, I show that it fails catastrophically for Christ's human nature in particular — and that the consequences for Christology are devastating.

The second book, The Heart of God: Does God Feel? A Biblical and Theological Case for the Emotional Life of God, argued that God has genuine emotional responses to His creatures. Against the classical doctrine of strict divine impassibility — the view that God cannot be affected by anything outside Himself and does not experience emotions in any meaningful sense — that book argued from Scripture that God truly loves, truly grieves, truly rejoices, and truly responds with compassion to His creatures' suffering. This is directly relevant to the Incarnation in at least two ways. First, if God genuinely feels, then the Son's decision to become incarnate was itself an expression of divine love — not a cold, detached decree but a personal act of self-giving. Second, Christ's human emotions in the Gospels — His sorrow in Gethsemane, His weeping at Lazarus's tomb, His compassion for the crowds, His anger at the money changers — are genuine expressions of His human soul. On physicalism, those emotions are nothing more than neurochemical reactions in a brain. On dualism, they are the inner experiences of a real human soul — a soul that feels, that mourns, that loves — and they reflect, in a creaturely way, the emotional life of God Himself.

The third book, The God Beyond the Clock: A Biblical and Theological Case for Dynamic Divine Temporality, argued that God is genuinely temporal — that He truly enters time, truly interacts with His creatures in real sequence, truly responds to prayer and events. Against the view that God exists in a timeless eternity where there is no "before" or "after," that book argued that God is everlasting — He has always existed and always will exist — but He genuinely experiences sequence, genuinely acts in time, and genuinely relates to His creation in real temporal flow. This is directly relevant to the Incarnation because the Son genuinely entered time. He was conceived. He was born. He grew. He learned. He suffered. He died. He rose. He ascended. These are real events in real time, and they require a God who can genuinely act within time. A strictly timeless God cannot become incarnate without falling into contradiction — for the Incarnation is, by definition, something that happened, a real event in real history.

This book is where all three themes converge. The Incarnation is where God's emotional life meets human emotion — in the soul of Christ. It is where God's entry into time becomes most concrete — in the lived human experience of Jesus. And it is where the question of human nature becomes most urgent — because the Son of God took on a human nature, and what that nature consists of determines whether the entire Incarnation holds together. In a sense, this book is the capstone of the series: the place where every thread comes together in the Person of Jesus Christ.

A Road Map: The Structure of This Book

This book is organized in six parts, with thirty-six chapters and five appendices. Let me give you a brief overview of where we are headed, so you can see the full sweep of the argument.

Part I: Foundations — What Is a Human Being? (Chapters 1–5) lays the groundwork. After this introductory chapter, Chapter 2 provides a comprehensive survey of the major models of human nature — from reductive physicalism to substance dualism — so the reader understands exactly what each view claims. Chapter 3 presents the biblical case for substance dualism, examining the key Old and New Testament passages that teach a body-soul anthropology. Chapter 4 presents the philosophical case for substance dualism, walking through the major arguments — from consciousness, personal identity, intentionality, and more — and responding to the major objections. Chapter 5 examines veridical near-death experiences as empirical evidence for the existence of the immaterial soul, drawing on my doctoral research.

Part II: Christ's Two Natures — The Biblical Witness (Chapters 6–10) turns from anthropology to Christology. Chapter 6 establishes the full deity of Christ from Scripture. Chapter 7 establishes the full humanity of Christ — body and soul — from Scripture, showing that the Bible explicitly attributes a human soul to Jesus. Chapters 8 and 9 explore Christ's human soul in the Gospels and Epistles respectively, examining His inner life, emotions, prayers, suffering, and death. Chapter 10 looks at Old Testament messianic prophecy and what it reveals about the humanity of the coming King.

Part III: The Church's Christology — Councils, Creeds, and History (Chapters 11–14) traces the development of orthodox Christology through the ecumenical councils. Chapter 11 covers the journey from Nicaea (325) to Chalcedon (451). Chapter 12 examines the rejection of Apollinarianism — the heresy that denied Christ a human soul — and explains why the church insisted that Christ must have a complete human nature. Chapter 13 examines Constantinople II and III and the completion of conciliar Christology. Chapter 14 provides a full treatment of the hypostatic union, dyothelitism (the doctrine of Christ's two wills), and the communication of attributes.

Part IV: Models of the Incarnation (Chapters 15–19) surveys and evaluates the major models for understanding how the Incarnation "works." Chapter 15 critiques kenotic Christology — the view that the Son emptied Himself of divine attributes. Chapter 16 examines Thomas Morris's "two-minds" model. Chapter 17 presents the author's preferred position: Loke's Kryptic Model with the Divine Preconscious framework. Chapter 18 engages Timothy Pawl's defense of conciliar Christology. Chapter 19 addresses the important concepts of anhypostasia and enhypostasia — technical terms for the way Christ's human nature exists "in" the Person of the Son.

Part V: Physicalism and the Incarnation — The Devastating Problems (Chapters 20–29) is the heart of the book's critique. These ten chapters systematically demonstrate that physicalism cannot account for the Incarnation. Chapter 20 states the problem comprehensively. Chapter 21 addresses Holy Saturday and the triduum mortis — what I consider the single most powerful argument against physicalist Christology. Chapter 22 examines the death of Christ and the dissolution of the hypostatic union on physicalism. Chapter 23 explores the descent to the dead. Chapter 24 tackles the resurrection and personal identity. Chapter 25 examines the virgin birth and the origin of Christ's human nature. Chapter 26 addresses the ascension and the permanent incarnation. Chapter 27 examines Christ's sinlessness and the Pelagian problem. Chapter 28 addresses the Trinity, personhood, and the physicalist challenge. Chapter 29 covers additional problems: the beatific vision, theosis, and sanctification.

Part VI: Responding to Physicalists and Applications (Chapters 30–36) rounds out the book. Chapters 30–32 provide a historical survey: the Church Fathers on Christ's human soul, the councils and the rejection of Apollinarianism, and the medieval-through-modern development of the consensus. Chapter 33 addresses physicalism and the conditional immortality movement specifically. Chapter 34 presents the comprehensive cumulative case. Chapter 35 answers the major physicalist objections and shows why they fail. Chapter 36 is the conclusion.

Five appendices provide additional reference material: a glossary of key terms, a comparison chart of Incarnation models, a Scripture index, a quick reference to the ecumenical councils' Christological definitions, and an annotated bibliography.

Why This Is Not Just an Academic Debate

I want to pause here and speak directly to you, the reader. I know that some of what I have described so far may sound abstract — hypostatic unions, substance dualism, the triduum mortis. These are technical terms, and I understand if your eyes start to glaze over when you encounter them. I promise that throughout this book, I will define every term in plain language and use concrete examples to bring every argument to life. But I also want you to understand why this matters — why this is not just an academic exercise for professors and seminary students.

This debate affects your understanding of who Jesus is.

When you pray, you are speaking to the God-man — someone who is both fully divine and fully human. But what does "fully human" mean? Does He have a soul like yours? Does He understand what it is like to feel grief from the inside, with a real human soul that aches? Or was His human experience just a matter of neurons firing in a first-century Palestinian brain?

This debate affects your understanding of what happened on the cross.

When Jesus died, did He cease to exist as a human? Did the Incarnation end, even temporarily? Or did His soul survive, so that He could carry your sins, descend to the dead, and emerge victorious?

This debate affects your understanding of what happened during the three days in the tomb.

Was Jesus' soul active? Did He descend to proclaim victory? Was He with the penitent thief in paradise that very day? Or was there simply a corpse in a tomb and an empty interval — three days when the Son of God was not incarnate, when God's union with humanity was broken?

This debate affects your understanding of whether the risen Jesus is truly the same person who died.

Is the Jesus who appeared to the disciples on Easter morning the same Jesus who hung on the cross? Or could He be a different being — a divinely created replica? What grounds the continuity of His identity through death and resurrection?

And this debate affects your understanding of who Jesus is right now.

At this very moment, Jesus Christ is at the right hand of the Father, interceding for you (Heb 7:25). He is still human. He is still the God-man. The Incarnation is permanent. But how? What holds it together? On dualism, the answer is clear: His human soul remains united to the Son, and His glorified body remains united to His soul. The Incarnation endures forever because both components of His human nature — body and soul — continue. On physicalism, the answer is far less clear.

These are not abstract questions. They are questions about the Person at the center of our faith. Getting them right matters enormously — not just for theological precision, but for worship, devotion, and the health of our souls.

The Church Has Always Known This

I want to be clear about something: the argument of this book is not new. I am not inventing a novel position or introducing a creative theory that no one has considered before. The church has always taught that Christ has a human soul. It has always insisted that His human nature is complete — body and soul. And it has always understood that without a human soul, the Incarnation cannot be what the gospel requires it to be.

This conviction goes all the way back to the earliest centuries of Christian thought. When the church father Irenaeus of Lyon wrote in the second century, he insisted that Christ assumed everything that belongs to human nature in order to redeem it. When Tertullian wrote in the third century, he affirmed that Christ's soul was real, distinct from His body, and essential to His human experience. When Athanasius defended the deity of Christ against the Arians in the fourth century, he also affirmed — without any hint of controversy — that the Word assumed a human body and a human soul.

The matter became explicit and urgent when Apollinarius of Laodicea proposed, in the late fourth century, that the divine Logos replaced the human rational soul in Christ. Apollinarius was not a heretic in the crude sense — he was trying to protect Christ's deity by ensuring that there was only one governing mind in Christ, the divine mind. But the church recognized immediately that this was a fatal error. If Christ did not have a human rational soul, then He did not have a complete human nature. And if He did not have a complete human nature, then He could not save the whole human person. Gregory of Nazianzus delivered the decisive blow: "What is not assumed is not healed." The councils of Constantinople (381) and Constantinople II (553) formally condemned Apollinarianism, insisting that Christ has a complete human nature with a rational, intellectual soul.³¹

This consensus has held throughout Christian history. It is not a position held only by some Christians, or by one theological tradition, or by one era of the church. It is the unanimous teaching of the Eastern Orthodox, Roman Catholic, and Protestant traditions. It is affirmed in every major creed and confession. Luther affirmed it. Calvin affirmed it. The Westminster Confession affirms it. The Augsburg Confession affirms it. The Council of Trent affirms it. The Orthodox confessions affirm it. Every branch of the Christian church, without exception, has taught that Christ has a genuine human soul.³²

What is new is not the position I am defending. What is new is the challenge to it. Christian physicalism — the view that humans are purely physical and have no immaterial soul — is a relatively recent development, gaining significant traction only in the last few decades. And it is this relatively new position that threatens to undermine what the church has always confessed about Christ's human nature. The burden of proof, I would suggest, lies heavily on those who would overthrow nearly two thousand years of unified Christian teaching on a matter this central to the faith.

The detailed historical survey — from the apostolic fathers through John of Damascus, from Aquinas through the Reformers, and into the modern period — will be provided in Chapters 30–32. But I wanted to flag this point here at the outset: the position defended in this book is the historic, orthodox, catholic (in the universal sense) Christian position. It is physicalism that is the newcomer, and physicalism that bears the burden of showing that its radical departure from the tradition does not compromise the doctrines the tradition was designed to protect.

A Note on Fairness and Method

Before I close this introduction, I want to say a word about how I intend to handle the opposing position. Throughout this book, I argue that physicalism is incompatible with orthodox Christology. That is a strong claim, and I make it with conviction. But I also want to be fair.

Christian physicalists — scholars like Nancey Murphy, Joel Green, Kevin Corcoran, and others — are serious thinkers who love Jesus and are committed to the authority of Scripture.²⁷ I do not question their faith or their sincerity. I believe they are wrong about human nature, and I believe their position creates devastating consequences for the doctrine of the Incarnation. But I will present their arguments as fairly and charitably as I can before responding to them. You should always "steel-man" the opposition — present their best arguments in their strongest form — before offering your critique. That is what I intend to do.

I should also note that many Christian physicalists may not have fully considered the Christological implications of their position. The focus of the physicalism-dualism debate in recent decades has been on philosophy of mind, neuroscience, and biblical interpretation — not on Christology. As the contributors to Christian Physicalism? Philosophical Theological Criticisms have shown, the Christological problems with physicalism are both numerous and severe, and yet they have received relatively little attention in the broader discussion.²⁸ I suspect that many physicalists would be genuinely troubled by the problems I raise in this book, because they may not have thought through what physicalism means for the Incarnation specifically. This book is, in part, an invitation to that conversation.

I also want to be transparent about my method. I am writing as a committed Christian who affirms the early ecumenical creeds, the definitions of the seven ecumenical councils, and the full authority of Scripture. I believe the Bible teaches substance dualism, I believe the councils require it, and I believe the philosophical arguments support it. I am not a neutral observer surveying the options from a distance. I am making a case. But I am making it honestly, with an open engagement with the best scholarship on all sides. Where I rely on the project's key reference works — Loke's A Kryptic Model of the Incarnation, Pawl's In Defense of Conciliar Christology, Farris's Introduction to Theological Anthropology, Wilkinson's Crowned with Glory and Honor, Cooper's Body, Soul, and Life Everlasting, and the multi-author volume Christian Physicalism? — I will cite them carefully and engage with them extensively.²⁹

A Pastoral Word

I write this book as a fellow believer. I am a Th.D. student — a learner, not a finished scholar. I have spent years studying these questions, and the more I study, the more I am convinced that getting Christology right is one of the most important things a Christian can do. Not because it makes you smarter. Not because it earns you points in theological debates. But because knowing who Jesus truly is — in all His divine glory and genuine humanity — transforms the way you worship, the way you pray, the way you live.

When I understand that Jesus had a real human soul — that He felt real sorrow in Gethsemane, that His soul was "very sorrowful, even to death" (Matt 26:38, ESV) — I know that He understands my grief from the inside. He does not merely observe my pain from a divine distance. He has been there. He has felt it. His soul has ached the way mine aches. The author of Hebrews tells us that Jesus was "tempted in every way as we are, yet without sin" (Heb 4:15, ESV). That temptation was not merely an external force pressing against a brain. It was an inner experience — a genuine struggle of a human soul, with a human will that had to choose, again and again, to submit to the Father. Because He has a soul like ours, He is the perfect sympathetic High Priest — one who truly understands what we face.

When I understand that Jesus' soul survived the cross and descended to the dead, I know that death has no dominion over Him — and because He lives, I will live also. The Incarnation was not interrupted. God's union with humanity was not broken. Not even death — the most powerful enemy of human existence — could sever the bond between the Son and His human nature. And that means my own union with Christ cannot be broken, either — not by death, not by suffering, not by anything in all creation. Paul's great declaration rings true: "For I am sure that neither death nor life, nor angels nor rulers, nor things present nor things to come, nor powers, nor height nor depth, nor anything else in all creation, will be able to separate us from the love of God in Christ Jesus our Lord" (Rom 8:38–39, ESV). The Incarnation's survival of death is the foundation of that promise.

When I understand that Jesus is still human right now — still the God-man, with a glorified body and a human soul — I know that He truly intercedes for me. He is not some distant deity who has moved on from the human experience. He is still one of us, even at the right hand of the Father. He still remembers what it was like to be tired, to be hungry, to be lonely, to be misunderstood, to weep over the death of a friend. He carries those human experiences with Him forever, in His human soul. And because He does, His intercession is not abstract or detached. It is personal. It is informed by experience. It is the prayer of someone who has walked in our shoes — and who never takes them off. He is our High Priest, our Mediator, our Brother. And He always will be.

I also believe that getting this doctrine right changes how we think about our own humanity. If Christ — the most glorious human being who ever lived, the perfect image of God — has a soul, then having a soul is not a philosophical embarrassment to be explained away. It is part of what makes us human. It is part of what makes us the creatures God designed us to be. The soul is not a Greek philosophical import that we need to purge from our theology. It is an essential part of who we are — and an essential part of who Christ is. When we deny the soul, we do not just create problems for Christology. We diminish our own humanity. We reduce ourselves to biological machines. We lose the rich biblical vision of the human person as a body-soul unity created in the image of God, destined not just for physical existence but for eternal life in the presence of our Creator.

The Incarnation is the most beautiful doctrine in all of Christian theology. And substance dualism — the view that we have souls — is what holds it together. That is what this book is about. I invite you to come along on the journey.

Let us begin.