Connecting Incarnation and Atonement


Icon of the incarnation

Andrew Purves, in his work, Exploring Christology and Atonement, says something very enlightening about the work of Christ: “Atonement is not so much a work of Christ apart from who he is, but rather Christ himself as work” (p 35).

What does this statement mean? He means to say that much of the western construals of the saving work of Christ are abstracted from who he is as incarnate God. Or to put another way, too many atonement theories disconnect Christ’s work from his identity. John McLoed Campbell says about the atonement: “The faith of the atonement presupposes the faith of the incarnation” (p 35). In other words, the theology of God’s incarnation cannot be detached from God’s work for us in his death and resurrection. The incarnation must inform what we believe about the work of the cross.

However, this is often not the case. Many theories of the atonement could and in fact do do away with the incarnation and still remain intact. The incarnation is an add on, an accidental necessity, not inherently necessary. Purves notes that many understand the atoning work of Christ as something “external to his person” (p 37). He quotes TF Torrance who calls this an “instrumental” view of the work of Christ. Christ took on human flesh, not because it was absolutely necessary, but to use as an instrument. He took our flesh in order to make payment, or to satisfy justice. However, he could have atoned in some other way.

Purves continues:

Such a view [of the atonement] need not but will likely tend toward a perspective on the atonement in which God needs to be propitiated in order to be gracious toward us. In such a view the love and forgiveness of God may be seen as the effects of the atonement. Further, an instrumental perspective on the atonement as an external work of Christ, as something that he does rather than having its ground in who he is, implies a corresponding view of our relation to Christ that is developed in terms of an external arrangement. In the scholastic Protestant tradition this is conventionally developed in terms of an imputed righteousness, in which, while we are and remain sinner, God, for Christ’s sake, regards otherwise… (p 37)

Put another way, Christ became man to give something externalized to God: Christ becomes man and gives God an externalized obedience, and God receives that on behalf of the sinner who, despite God’s forgiveness, remains a sinner. This type of atonement theory does not really need the incarnation. Christ became man so that as a man he could offer a receipt of obedience and payment; but he could have made atonement as the divine Son without his humanity.

Purves is right in noting that this view becomes very common in the scholastic Protestant tradition. For instance, in the Heidelberg catechism, it is asked, why did God become man? The answer:

He must be a true man
because the justice of God requires
that the same human nature which has sinned
should pay for sin.
He must be a righteous man
because one who himself is a sinner
cannot pay for others (Q 16)
Notice, why did God become man? There is nothing necessary in this incarnation except that as man Christ can now pay a price for sin. This is a legal reality located outside of the inner logic of the incarnation. It presumes that perhaps Christ could have paid for sin without becoming fully man.


But now, if we are to connect the incarnation to the atonement, as Purves says, what new theological situation do we find ourselves in?

On the other hand, it is precisely the union of the incarnation and the atonement that excludes the view of the atonement is reducible to a forensic transaction as fulfilling of a legal contract, or to Christ propitiatingly bearing the cost construed as divinely meted punishment… [Rather], an ontological rather than an instrumental connection must be made between the Christ who makes atonement and the atonement that he makes. Or, in a different set of images, we look for an organic and personal rather than a mechanical and legal connection between Christ and his atonement and ourselves (p 37-38)

If the incarnation is an ontological, metaphysical reality, then the atonement itself must be posited from within the humanity of Christ, rather than legally outside of Christ. It must be seen organically, rather than extrinsically.

Purves explains the atonement in terms of a “magnificent exchange”. This is a term that began with the early fathers, but was also received and used both by Calvin and Luther. The magnificent exchange grounds the atonement in God’s work of the incarnation. A key text used by all the fathers was 2 Corinthians 6:9:

For you know the generous act of our Lord Jesus Christ, that though he was rich, yet for your sakes he became poor, so that by his poverty you might become rich.

Purves explains how the fathers and early reformers understood this verse:

Christ exchanged his place with our place in an atoning reversal of our status, making an atoning exchange. Christ puts himself in our place so that in him we might be put in his place. This is the meaning of reconciliation, which is an act effected on the basis of exchange (p 104)

In other words, the incarnation relates to atonement by way of an exchange of places. This isn’t a legal exchange: it’s an actual exchange. Christ became what we are so that we might become what he is. Purves continues:

The magnificent exchange must be set in the context of the whole movement of Christ in his descent and ascent… From this we see that the magnificent exchange is not at its core something that Christ does; rather, it is the working out of who he is in his history in our flesh. Christ is the magnificent exchange as God’s gracious saving movement toward us. In himself Christ is the word/act of God to us, and he is the responding and acceptable filial human movement toward God (106)

This is a great passage. Purves rightly says that in himself Christ is God condescended to us in our fallenness and sin, and in our humanity Christ is the perfect filial response of man to God. Thus there is atonement in his own person. God and man are united in this one divine Person.

Thus we can see: the incarnation is itself atonement. God the Son unites himself to us, and in a downward/upward movement makes God and man at one. As Purves says: Christ does who he is!





What is the meaning of the atonement? A proposal


Harrowing of Hell by Duccio di Buoninsegna ca. 1255 – 1319 (source)

At basic, the atonement is the doctrine of what God did to unite man with himself. Assumed in this doctrine is of course a foundational doctrine of original sin: mankind is not one with God, and thus needs to be made one.

Among the differing opinions of just what God has done to reconcile with mankind are two options.

One option is what we might call the legal doctrine of atonement. This legal atonement is posited in one of two ways: the Anselmian type and the penal substitution type. Both of these versions posit that the principal thing that separates man from God is the legal offense of sin. And thus, the thing to be removed is this offense.

Anselm posited an atonement theory which essentially proposed that God is offended by our sin, and Christ offers himself up to the Father as a satisfaction for sin. It is his self-gift which “covers our offense” and thus God forgives us. A more modern theory is commonly called penal substitution: in order for God to unite with man, he in fact must punish sin. Christ is punished by the Father in our place, and thus our sins are removed.

Without wholesale rejecting truths in these construals, I have issues. The struggle I have with these theories is that the problem the atonement means to solve is found in God: God is offended, and that is the thing that keeps us from reconciliation. Of course, our sin is offensive. But I wonder: why would that offense demand the death of the Son? Why couldn’t something else be done to rid the offense of sin? Is God unable to forgive without some sort of satisfaction? To be sure, it is said in scripture that Christ is a sacrifice for sin. Like the sacrifices of the Old Testament, Christ becomes a holy offering, a gift given over to the Father. And yet, I have yet to find it stated as such that without it God could not forgive us. To be sure, as well, we are said to be received into fellowship “for the sake of Christ”, something that the Reformation rightly recognized: we are not the cause of our salvation. Christ himself is the cause. He is our advocate before the Father. But again, this does not follow that Christ had to bear God’s wrath for our forgiveness. God receives us rather for the sake of who Christ himself is: he is the righteous servant, the obedient Son.

Patrick Henry Reardon rightly mentions that in Jesus’ parables, there is an assumption that forgiveness is something that, if it is to be forgiveness (!!), must be given freely without payment. Reardon says this:

The image of man’s “debt” owed to God is, of course, perfectly biblical. Jesus spoke of God as “a certain creditor who had two debtors” (Luke 7: 41). He also described the judgment of God as the summoning of the master’s debtors (16: 1– 12). But with regard to this debitum of the Lord’s parables, we encounter an immense irony: It is the whole point in these parables that the debt is not paid; it is simply forgiven. As the Church Fathers understood these parables, they refer not specifically to the work of Christ, but to the mercy of God and to man’s obligation to imitate that mercy.  (Reclaiming the Atonement, Kindle 816-821)

By God’s mercy he releases us of our debt. Our justification is through Christ, “for the sake of Christ” yes, but that is not the same as saying that God forgives us because he punished Christ.

With all that said, I do accept some legal aspects of the cross. However I do not think that the primary purpose of the cross was to remove a legal barrier of God’s offense to our sin. He does hate our sin, to be sure. But in my estimation we must locate the reason for the cross elsewhere. The atonement makes us at one with God for yet another reason.

I would like to propose a second type of atonement which I would like to call participatory atonement:

Gerhard Forde once wrote that God is only “satisfied” when he recreates sinners who are no longer under wrath. “Christ’s work, therefore, ‘satisfies’ the wrath of God because it alone creates believers, new beings who are no longer ‘under’ wrath” (A More Radical Gospel, 97). In this sense God is doesn’t need payment so much as he desires to remove the barrier of sin from his people.

Of course, this still doesn’t help us understand the atonement, but it does help us to understand the real barrier: the problem isn’t God but rather us. We are the sinners who have been so corrupted and lost, that it will not suffice for God to simply forgive us. We must be radically recreated. But how does this recreation happen, and even more, how does this relate to the atonement? What I want to propose is that the atonement is nothing less than God’s radical solidarity with us in our sin, a traveling down into the depths of our fallenness in order to recreate us and raise us up.

Robert Jenson, in his Systematic Theology volume 2, says that the atonement is what it costs God to remain our loving Father; or, to remain in union with his people, to be in fellowship with humanity. What did it cost? How could he remain our Father even in the midst of our sin? Very simply, it cost him death. In order for him to remain what he wanted to be for us, he had to die.

But why death? Why the gruesome reality of the crucifixion?

Well, because that was our reality. We were in sin and death and corruption and fallenness. We were a broken mess. God could have in his sovereign legal power simply acquitted us of our wrongs, but that would not have been enough. It would not have changed our fundamentally fallen situation. And so, he had to do something about it. And what he did, was he stepped into our fallen situation. This is the fundamental point of the incarnation: God steps into our situation to redeem it.

Reardon explains it this way:

[T]he Incarnation was far more than a condition for our salvation. It served, rather, as the effective model and exemplar of salvation. The Church Fathers insisted that the “full humanity” of Jesus Christ was essential to man’s redemption, because “whatever was not assumed was not redeemed.” (Reclaiming the Atonement, kin loc, 93-94)…

[I]f the fact of the Incarnation means that the Word adopted the fullness of human experience— sin excepted, says the Epistle to the Hebrews— then nothing human can be excluded from the study of redemption. The Word, embracing our humanity, took possession of all of it in order to redeem all of it. (231-33)

Reardon goes on to say that Christology is soteriology. God became man. God took on the fullness of our experience; and why did he do that? To redeem it; to transform it; to renew it; to glorify it. The early fathers of the church were fond of reversing their Christology in order to explain salvation: God became man; why? So that man might become God. By that they meant that God came down to raise us up. Christology is soteriology.

David Fagerberg explains it this way: “Our deification (sanctification) is twinned to Christ’s Incarnation. Mankind enters into the life of God because of his hypostatic union” (Consecrating the World, p 60). Fagerberg quotes John Chrysostom who says this about the incarnation and resurrection: “Two things He has done, the greatest things. He has both Himself descended to the lowest depth of humiliation, and has raised up man to the height of exaltation.” (ibid, 61)

Thus God condescended into our midst, into the brokenness of our situation, to redeem and raise us up. We may call this a model of participation or solidarity. God becomes what we are — sinful, broken, fallen — in order to make us what he is.

Thus the incarnation, cross, resurrection, ascension, must be seen as a whole. The cross is very simply the deepest depth of our fallen condition. Christ travels into the realm of death and defeats that reality, what the Eastern fathers called the harrowing of hell (icon above). God the Father vindicates (justifies) Christ from the dead, and enthrones our human nature at his right hand.

Mark A. McIntosh says this of the cross:

What we see happening in Christ on the cross is the stretching out of God to us in our affliction and separation from hope. There, in Jesus’ cry of dereliction, we see the Word of God finding us, sharing our plight, crying out to the Father. Our lostness and distance from each other and from God has been embraced within the “distance” of God’s eternal life of love, embraced within the love of the Father for the Son and the love of the Son for the Father, that one love — the bond of supreme union… — whom we know as God the Holy Spirit… Our suffering is forever embraced and suffered within this eternal loving which is God’s life. (Mysteries of Faith, 38-39)

In love, in forgiveness, God comes into our death, enters into our darkness, and embraces us so as to transform us. Salvation then is the reception of this embrace. We are acquitted of our wrongs “for the sake of Christ” and raised up and seated with Christ on high, removed from our fallen situation.

Apollonarianism: The First Christology


I am reading through the Russian Orthodox theologian Sergius Bulgakov’s seminal work The Lamb of God. And I decided that I would (try to, at least) blog through this work. The work itself is Bulgakov’s Christology, or what he calls the divine-humanity. The question he asks throughout is: how is the divine humanity possible? Or, put another way: how is the union of God and man in Christ in reality even a possibility?

I want to begin with a few posts outlining Bulgakov’s highly important introduction. This introduction, which is quite long — a whopping nearly 90 pages — is a captivating survey of the patristic Christology. He surveys how the earliest church understood Christ’s divine humanity, which he understands as a long process of positive and negative development. He is surprisingly critical of much of the early fathers of the church, particularly of Cyril of Alexandria and the great Athanasius. I must admit that I was a bit put off by some of his negativity, especially of Cyril; but I must also admit that much of his critique was quite valid.

Bergakov begins the introduction by surveying Apollonarius’ theology. I want to devote this first post to Bulgakov’s recommendation of Apollonarius as the first theologian to actually articulate a Christology. That Bulgakov recommends Apollonarius may seem surprising by some, especially because his Christology is historically deemed as heretical. However, he starts there because, as he says, Apollonarius “was the first to pose the problem of divine-humanity” (p 3). Bulgakov goes so far as to say that the epoch of Christology “originates with his problematic” (p 3). What he means here is that Apollonarius was the first to pose just how God and man, by definition two differing beings, can fit together in the one person of Jesus Christ. Bulgakov explains:

Apollonarius was the first to consider a fundamental problem of Christology: What is the divine-humanity? Or, how is the incarnation possible? What does it presuppose? Apollonarius went beyond the naive physical notions of his predecessors, who were satisfied with the soteriological postulates of the incarnation and the affirmation of the fact of the latter. He began to analyze this fact, and from this analysis, Christology was born (p 4)

Bulgakov makes an important point: Apollonarius was the first to ask how it is that Jesus is God and man at the same time. How do they fit together in a unity which makes logical sense? Strictly speaking, before Apollonarius, the Fathers were content with saying things like “God assumed a human nature” or “the divine Son became a man”. This is Bulgakov’s problem with many of Athanasius’ schematics. While Athanasius was a great defender of the faith against Arianism (that the Son was a lesser demi-god), he still did not articulate how the Son was both God and man. And, while the Chalcedonian definition is creedal and therefore a “non-negotiable”, even that is minimal in its affirmation: the Son is consubstantial with God the Father and man. But, again, what does that mean? Apollonairius was the first to posit a solution to the problem.

Bulgakov explains this problem more in depth:

What meaning an we attach to this becoming (genesis) of the Word, who in himself possesses divine unchangeability but who assumes flesh, “becomes incarnate and is in-humanized” (these two notions being equated according to the Nicene Creed)? The flesh denotes the body and thus refers to man’s creaturely corporeality, which is opposed to the noncreaturely spirituality of Divinity. The in-humanization is thus defined, first of all, as the assumption of a body. We find this doctrine in  particular in St. Athanasius: to express the doctrine of the incarnation, he is content to use the notions of soma (body) and sarx (flesh). Strictly speaking, there is no Christology here. (p 8)

What Bulgakov means here is that this isn’t really a postalizing about how the Son is incarnate: it’s just stating the matter! Apollonarius, whether for ill or good, was the first to give some sort of explanation.

But what was Apollonarius’ Christology? Before explaining, it is first important to note that Apollonarius’ intention in his Christology was to protect the unity of the God-man. Christ, as Apollonarius says, “is not two persons, as if one God and the other man” (p 5). Christ is one person somehow containing two natures. Another thing Apollonarius set out to do was to protect the unchangeability of the divine nature. God does not become anything, nor can he. So how can the unchangeable God become man? With these two boundaries set, Apollonarius set forth a Christology. Bulgakov explains:

According to [Apollonarius’] theory, the Logos [the Son] replaced, in the human essence of the God-man, the supreme principle of man, which Apollonarius calls (in the language of Hellenistic philosophy) pneuma or nous and which corresponds to the hypostatic spirit in man’s nature. (p 8)

Put another way, when the divine Son became united to the human nature, the divine nature replaced something within the human nature, thus “fitting” together in one person. To the historically astute, this articulation inevitably paves the way for monophysitism, the thought that the union of God and man in Christ creates a third single nature. This is not how Apollonarius understood it, however. In his mind, this articulation protected the unity of the God-man and the unchangeability of the divine nature.

It is also important to acknowledge that it is unclear what exactly Apollonarius meant by the terms pneuma or nous. In some places in his writings it seems like he means man’s soul or spirit. But in other places it seems like he means man’s intellect: “How does God become man without ceasing to be God if God does not take the place of the intellect of man?” (p 11). Bulgakov also notices importantly that Apollonarius believed man to be composed of three parts: body, soul, spirit. This means that Apollonarius almost certainly still understood Christ to have a human body and soul. So then, what part of the human nature did the divine replace, and how does it all fit together into a unity? There is confusion on this, but Bulgakov explains:

Apollonarius’ conception is …interpreted to mean that Christ assumed an incomplete human essence, namely body and soul, but without the human reason, which is replaced by divine reason. That is precisely how Apollonarius’ theory was interpreted by his contemporaries and his opponents, by St. Gregory the Theologian and in part even by St. Gregory of Nyssa. (p 13)

Bulgakov argues that this is not necessarily how Apollonarius meant it. His language was very imprecise, and he could have meant nous to be another part of the human person. In any case, the early church rejected Apollonarius’ Christology because they understood him to mean that the divine Son assumed a human nature devoid of human intellect or the human mind. If that was the case, it meant that the Son assumed an incomplete human nature. And this is of course where St. Gregory of Nazianzas’ famous saying came from: “Whatever is not assumed is not healed”. If Christ had not assumed a complete human nature — including the human mind — than the human nature as such is not fully regenerate, and thus salvation is not possible for mankind.

While agreeing with the church on this, Bulgakov makes this general observation before moving on in his introduction:

[Apollonarius’] errors did not find adherents in dogmatics; on the contrary, it was the positive aspects of his doctrine that were adopted and endure in dogmatics. In this sense there is an essential difference between Apollonarius and Arius, with whom he is sometimes compared with reference to Christology: Although Arius did awaken the dogmatic consciousness, gave rise to the homoosian movement, and was indeirectly responsible for the Nicene Creed…, his proper doctrine represents a direct rejection of the truth, pure falsehood without any ambiguity. In contrast, in Apollonarius’ doctrine everything has a double meaning; everything is a mixture of truth and error. In this respect he does not greatly differ from certain fathers who are honored as teachers of the Church…

But the access into historical dialectic Christology lies through Apollonarius’ theological doctrine, and this constitutes his enduring historical significance and, of course, his great achievement in behalf of the church. (p 18-19)

It is a bit odd to find Bulgakov speak so highly of this heretical Christology; and yet, I cannot disagree with Bulgakov. Apollonarianism was the first achieved Christology. Apollonarius meant to makes sense of Christ as one person, as a unity, yet being composed somehow of two natures. In the next post we will move to St. Cyril of Alexandria and his opposition to Apollonarius.


The Christological Heresies: Arianism

Continuing in my examination of the early church heresies concerning Christ, in this post I want to consider the Arian heresy.

That Christ was human was, to the earliest church father, fairly self-evident. But, was Christ just human? Was he also divine? And if he was divine, how divine was he? And how did this square with the Jewish concept of monotheism? This was the question of the earliest theologians of the church.

During the first century, the church dealt with different heresies concerning this question: on the one side, an early Jewish sect of Christianity, Ebionitism, posited that Jesus was not divine at all; He was simply an Old Testament prophet. On the other side, Docetism (akin to Gnosticism) taught that Christ was only divine, and that his human nature was only apparent, but not real.

The earliest fathers knew to reject these extreme positions. But their Christology was still being developed. We can see this by looking at Justin Martyr. An early church apologist, Justin was the first to write on Christ’s divine nature. He taught that Jesus Christ was the incarnation, or revelation, of the eternal Logos (knowledge) known from Platonism.  

Alister McGrath explains:

Justin developed… the idea of the “Logos”, current in both Stoicism and Middle Platonism of the period. The Logos (logos is a Greek term usually translated as “word” — eg, as it is found at John 1:14) is to be thought of as the ultimate source of all human knowledge. The one and same Logos is known by both Christian believers and pagan philosophers; the latter, however only have partial access to it, whereas Christians have full access to it, on account of the manifestation in Christ. Justin allows that pre-Christian secular philosophers, such as Heraclitus and Socrates, thus had partial access to the truth, on account of the manner in which the Logos is present in the world.

An idea of especial importance in this context is that of the logos spermatikos (seeds of the Word), which appears to derive from Middle Platonism. The divine Logos sowed seeds throughout human history; it is therefore to be expected that this “seed-bearing Logos” will be known, even if only in part, by non-Christians. Justin is therefore able to argue that Christianity builds upon and fulfills the hints and anticipations of God’s revelation which is to be had through pagan philosophers. The Logos was known temporarily through the theophonies (appearances of God) in the Old Testament; Christ brings the Logos to its fullest revelation… (Historical Theology, 42)

After this, another church father, Origen, borrowed and completed Justin’s thoughts:

It is in the writings of Origen that the Logos-Christianity appears to find its fullest development. In the Incarnation, the human soul of Christ is united to the Logos. On account of the closeness of this union, Christ’s human soul comes to share in the properties of the Logos. Nevertheless, Origen insists that, although both the Logos and the Father are coeternal, the Logos is subordinate to the Father. (ibid, 42)

The Logos-Christology is insufficient: it fails to answer questions concerning the unity of God, and the nature of how the Logos relates to God the Father. However, this helps give context to the Arian controversy. We can observe that the church fathers were wrestling with how exactly to call Christ divine. Justin and Origen opted to use Platonistic categories, explaining Christ as this eternal “Logos” which was only partially known until his full revelation in Christ.

During this time of wrestling, Arius emerged with a view of his own that would proved very controversial. It must be noted that historians know very little about Arius and his life. Even more, we have access to his views only through his opponents.

Generally, however, we know that Arius regarded Christ as being a created being. He is known for saying “there was when he was not” of Christ. God is the only uncreated being. Christ, the Son, is a created being who, while being pre-existent and higher than other beings, is still below the Father.

Alister McGrath explains:

The Father is regarded as existing before the Son…This decisive affirmation places the Father and Son on different levels, and is consistent with Arius’ rigorous insistence that the Son is a creature… There is a distinction of rank between the Son and other creatures, including human beings. [However], Arius has some difficulty in identifying the precise nature of this distinction. The Son, he argues, is “a perfect creature, yet not as one among other creatures; a begotten being, yet not as one among other begotten beings”… (ibid, 44)

So while the Son does pre-exist other creatures, and is perfect above them, he is still created and thus below the Father. For Arius, this explained the balance of scripture: Christ was above all other creation, but distinct from the Father.

How did the early church respond to this position? And what was wrong with Arius’ position?

Saint Athanasius wrote a critique of the Arian position called Against the Arians. McGrath explains Athanasius’ critique:

For Athanasius, the affirmation of the creaturehood of the Son had two decisive consequences, each of which had uniformly negative implications for Arianism. First, Athanasius makes the point that it is only God who can save. God, and God alone, can break the power of sin, and bring us to eternal life. An essential feature of being a creature is that one requires to be redeemed. No creature can save another creature. Only the creator can redeem the creation. Having emphasized that it is God who can save, Athanasius then makes the logical move which the Arians found difficult to counter. The New Testament and the Christian liturgical tradition alike regard Jesus Christ as Savior. Yet, as Athanasius emphasized, only God can save…

The second point that Athanasius makes is that Christians worship and pray to Jesus Christ. This represents an excellent case study of the importance of Christian practices of worship and prayer for Christian theology. By the fourth century, prayer to and adoration of Christ were standard features of the way in which public worship took place. Athanasius argues that if Jesus Christ is a creature, then Christians are guilty of worshipping a creature instead of God (ibid, 44-45)

God is the only Savior — if Christ is Savior, then he is God. Only God deserves worship — if Christians are called to worship Christ, then he is God!

The debate over the Arian controversy came to a close with the formulation of the Nicene Creed, which declared that Christ was “homoousios” of the Father. This is a Greek term which means that Christ is “of the same substance” of the Father. Or, put another way, Christ is the same nature, equal to the Father. This of course logically leads to an affirmation of one divine being with distinct persons — the Trinity!

The Christological Heresies: Apollinarianism

During the first five centuries after its conception, the church was forced to deal with several different heresies concerning Christ. In fact, the church was forced to formulate a concise universal statement about the nature of Christ (Nicene Creed), because of the many differing heresies proposed during its infancy.

Most of these heresies centered around the nature of Christ, his humanity and divinity. How divine was Christ, really? How human was Christ, really? And how do these natures interact with one another?

In the next few blog posts, I want to consider a few of the more famous Christological heresies. In this post, I want to consider what is called the Apollinarian heresy:

By the fifth century, it became orthodox to believe that God in Christ had assumed a full human nature for our redemption. The eastern church had coined a phrase which is still prominent today: “God became man that man might become God” — and by that, they meant that God became fully man, that we might participate fully and redemptively in His very life. The thought was that if God wanted to assume and redeem mankind back into fellowship with him, he needed to become fully human in the incarnation to raise us back to glory.

One bishop name Apollinaris (after whom was named this heresy), however, was uncomfortable with affirming that God the Son became fully man. To him, to become fully man was to taint the divine nature.

Allister McGrath explains:

Apollinaris of Laodocia had anxieties about the increasingly widespread belief that the Logos (God the Son) assumed human nature in its entirety. It seemed to him that this implied that the Logos was contaminated by the weaknesses of human nature. How could the Son of God be allowed to be tainted by purely human directive principles? The sinlessness of Christ would be compromised, in Apollinaris’ view, if he were to possess a purely human mind. Was not the human mind the source of sin and rebellion against God? Only if the human mind were to be replaced by a purely divine motivating and directing force could the sinlessness of Christ be maintained. For this reason, Apollinaris argued that, in Christ, a purely human mind and soul were replaced by a divine mind and soul: “The divine energy fulfills the role of the animative soul and of the human mind” in Christ. The human nature was thus incomplete. (Historical Theology, 47)

Apollinaris thus promoted the view that the divine nature of Christ “replaced” the human soul and mind, protecting him from the corruption of human sin. One can almost picture the human nature of Christ like a puppet. The problem with this view of course, was that it made Christ not fully human. He merely appeared to be human, but was in fact only outwardly human, not having a human mind or soul.

The early church rejected this notion for one massively important reason: if Christ was not fully human, he could not fully redeem the human race! If the goal of redemption was to welcome fully humanity back into fellowship with the Godhead, how can a half-human Christ redeem whole humanity?

Gregory of Nazianzus, theologian of the fourth century, replied famously to Apollinaris by saying: “what has not been assumed has not been healed”. If Christ did not assume a “fallen” human mind, or soul, how can the mind and soul be redeemed? The answer is that it cannot!

McGrath explains:

For Gregory, only aspects of human nature which have been united to divinity in the incarnation are saved. If we are to be saved in the totality of our human nature, that totality must be brought into contact with the divinity. If Christ is only partly human, then salvation is not possible.(ibid, 49)

The biblical record of course agrees with this. Hebrews 2:17 says that Christ…

had to be made like his brothers in every respect, so that he might become a merciful and faithful high priest in the service of God, to make propitiation for the sins of the people”.

Christ had to be made like his brothers “in every respect”. What this means is that while God the Son had a fully divine nature, he also had a fully human nature. For this reason, Christians affirm that God the Son is one person with two natures. When asked who was acting in the person of Christ, we answer the eternal Logos. But when we ask about the what, we must reply: full divinity and full humanity.