The human person’s correspondence with the eternal person of the Son maintains the value of every human being near the end of life on this earth, regardless of their quality of life or how “useful” society thinks they are. And thinking of a more recent issue like artificial intelligence, a human “I” that is the acting subject of a body and soul provides a clear ontological line that protects real human beings from devaluation by our own inventions.

What are we as human beings? Are we simply a body and a soul, as most have thought in Christian theology? Or are we something different, more or less? In Part 1, we started to answer the question by looking to the man Jesus Christ. In two theses for what I am calling a “Chalcedonian anthropology,” we thought through the biblical logic of how the incarnation makes the gospel “work,” which gave us good biblical warrant to define human being in Christ.

In this Part 2, we’ll continue looking to Christ until we have a clear understanding of our own human being. If Christ is the paradigm for all things truly human, including what makes us human, then we need to know what makes him fully human. Fortunately for us, the early church already answered that question. The Chalcedonian Definition tells us both that and how the divine Son’s incarnation made him a complete man, like us in every way, but without sin. So in this article, we’ll walk through the last three theses of a Chalcedonian anthropology. We’ll consider the early church’s pattern for answering the what question of Christ as the God-man and apply it to answer the what question of mere man. Following the dogmatic logic in moving from God the Son to God the Son incarnate will give us solid historical warrant for extending that logic from Christ the man to all mankind.

In the end, this will give us an anthropology “from above.” Allowing the humanity of Christ to govern our understanding of our own humanity will give us a greater appreciation for the depth of human dignity and the wisdom of God in the incarnation of the Son. It will fortify a critical link in our systematic theology. And it will equip us to confront the man-centered issues of our day in a Christ-centered way.

Let’s begin with the third thesis of a Chalcedonian anthropology.

3. Chalcedon confesses that Christ is fully man in the same basic way he is fully God.

In the fifth century, the church needed a coherent way to confess that Christ is both fully God and fully man. Scripture requires this unity and distinction. But leading up to Chalcedon, the major attempts to make sense of the divine Son’s incarnation were insufficient. Nestorius and Cyril of Alexandria both affirmed that the divine Son was made like us, not by replacing the human soul, but by becoming a complete man.[1] Yet neither of them could account well for both a real distinction between the deity and humanity of Christ and their unity in only one Son.

So at Chalcedon (451 AD), rather than trying to modify or merge different explanations for how the divine Son became a man, the church looked to its earlier confession that the divine Son is God prior to his incarnation. Thus, to understand how Chalcedon defines Christ as fully God and fully man, we first need to look briefly at Trinitarian orthodoxy.

Fair warning: things are going to get a bit deep and technical. But the terms and concepts ahead are the best way to understand and confess what Scripture requires. And heads-up that “person” doesn’t mean what might think. Hang in there … it’s worth it.

Person-Nature Being of God as Trinity

In the Trinitarian debates of the fourth century, the church needed a coherent way to confess the mystery of the Trinity. Most agreed that there is one God and there are three who are God, namely, the Father, Son, and Spirit. The disagreement centered on how to make at least basic sense of that truth. Because Scripture clearly reveals that it’s true, there must be a reasonable explanation of how God is both one and three.

So the church needed an ontological solution to accomplish its dogmatic task of defending and proclaiming the Trinity. Unfortunately, the theologians of the day used different terms and concepts, and sometimes they used the same ones differently. As if things weren’t complicated enough!

The breakthrough finally came with the development of the person-nature distinction. Beginning with the Creed of Nicaea (325 AD), the church repurposed ordinary terms and concepts to do the theological work required to confess that God is three persons (hypostases) in one nature (ousia). That is, the Father, Son, and Spirit are each a distinct divine person that subsists in the single-same divine nature.[2] More specifically, each is a subject/self/“I” who is fully and equally God precisely because each person subsists fully and equally in the divine nature.

The divine persons are not the same thing as the divine nature, they’re not parts of the divine nature, and they’re not separate from the divine nature. Those would lead to the heresy of modalism (not three distinct persons) or tri-theism (three separate gods). Rather, hypostasis (person) and ousia (nature) are intimately related in the Trinity, but they are distinct ontological realities: person is a subsistence that provides existence to a nature; nature is a substance that exists in a person. Yet this person-nature distinction does not divide God into three divine beings because the persons equally and fully share the same nature and perfectly indwell one another (coinherence). Gods’ nature is singular and simple in that it cannot be parted or partitioned.

Simply put, person and nature are distinct from one another, but both are necessary elements. God is a person-nature being.

Thus, by the end of the fourth century, the church had made ontological sense of the Trinity through the person-nature distinction. The full Nicene Creed of 381 AD confesses that there is only one God (according to nature), and there are always three who are God (according to person).  The Father, Son, and Spirit are who God is according to person (hypostasis); one divine being is what they are according to nature (ousia)

Person-Nature Being of God the Son Incarnate

At Chalcedon, then, it was this particular distinction between person and nature that the church used to confess that the divine Son, the second hypostasis of the Trinity, became a man, our Lord Jesus Christ.  The Definition says:

We . . . teach men to confess one and the same Son, our Lord Jesus Christ, the same perfect in Godhead and also perfect in manhood; truly God and truly man, of a reasonable soul and body; consubstantial with the Father according to the Godhead, and consubstantial with us according to the manhood; in all things like unto us, without sin . . . to be acknowledged in two natures, inconfusedly, unchangeably, indivisibly, inseparably; the distinction of the natures being by no means taken away by the union, but rather the property of each nature being preserved, and concurring in one Person . . .

Thus, the center of God’s grace to the church at Chalcedon is the person-nature analogy that confesses how the divine Son’s incarnation made him a real and complete human being! On the divine side, Christ is fully God because the divine person (hypostasis) of the Son subsists in the divine nature (ousia). That’s how the eternal Son is “consubstantial” (homoousios) with the Father (and the Spirit). On the human side of the analogy, Christ is fully man because the same divine person (hypostasis) of the Son now also subsists in a complete human nature (ousia), which is a “rational soul and body.” That’s how the incarnate Son is “consubstantial” (homoousios) with us. That’s how the Word, the eternal Son, became flesh and dwelt among us (John 1:1, 14).

At this point, it’s crucial that we slow down and identify a lynchpin of orthodox Christology: the divine person of the Son is the person of Christ.

Just after Chalcedon, some erroneously interpreted the one “person” in the Definition to be the Lord Jesus Christ. That is, the Son’s incarnation resulted in the unique divine-human “person” (a kind of composite) who is the whole “person” of Christ. That’s similar to what we mean today by saying a particular, whole individual is a “person”—body, soul, mind, emotions, etc. But if applied to Christ, that would lead us into the heresy of Nestorianism that argued that Christ had two persons, one divine and one human.

In contrast, it’s crucial to note that the church insisted that “person” must have the same meaning as in the Trinity! The incarnation did not create a distinct human “person” or a composite “person.” Rather, the one and only “person” of Christ is none other than the divine hypostasis of the Son. We confess that Christ is both fully God and fully man because his divine and human natures are located specifically in the eternal person (hypostasis) of the divine Son.

So Chalcedon teaches that we must see Jesus Christ as a person-nature being to make sense of the fact that he is God the Son incarnate. The Chalcedonian analogy presents a person in a nature on the divine side and then the same person in a different nature on the human side. Christ is both fully God and fully man because the same divine person of the Son who subsists eternally in the divine nature has come to subsist forever in a human nature.

This repetition of a person-nature constitution in Christ does not create two persons or beings because the divine and human natures concur in “one person”/subsistence/hypostasis. As with the Trinity, hypostasis and ousia are intimately related in Christ, yet they remain distinct ontological realities: person is still a subsistence; nature is still a substance. But the reduplication does mean that Christ has two distinct person-nature ontologies, one fully divine and the other fully human.

Of course, extending the person-nature distinction from the Trinity to Christ required some adjustment. The same divine person (the Son) is the pivot point of the Chalcedonian analogy: he is God according to his divine nature and now man according to his human nature. But these two natures are each complete and distinct from the other, and each nature retains its original integrity. As the Definition says, the incarnation did not change or confuse the natures, “the property of each nature being preserved,” even as they now exist together in the divine person of the Son. So the natures are the same in that each is an ousia. Yet they’re different in that one is completely divine and the other is completely human. In this way, the extension is analogical.

Even with that adjustment, however, the Chalcedonian analogy holds. The divine Son is fully man in the same basic way that he is fully God: through a person-nature constitution.

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