Many churches across the denominational spectrum celebrate the incarnation of Jesus Christ around this time of year. We sing Christmas carols and hymns about the incarnate deity, and yet many Christians still lack a rudimentary understanding of what took place in the incarnation. Now, let’s be honest, the incarnation is one of the great mysteries of the faith! We’re never fully going to wrap our minds around it. Yet, I wonder if it might not do us good to hear from (perhaps for the first time) some of the men who, over the centuries, helped shape the church’s theology on this very question.
Irenaeus (130-202) was one of the greatest defenders of the Christian faith. In his most famous work, Against Heresies, he described the apostolic Christian faith as “believing in one God, maker of heaven and earth and of all things in them, through Christ Jesus, the Son of God, who, on account of his surpassing love for his creation, endured to be born of the Virgin, himself in himself uniting man with God” (III.IV.2).
Note here that, for Irenaeus, it is the love of Jesus that leads to the incarnation and that the incarnation was itself in some way a “saving” moment for humanity. When God the Son took flesh from the Virgin’s womb, he was uniting our nature with his and, in doing so, paved the way for the restoration of fallen men and women.
The first non-negotiable we find in the Fathers is that the incarnation is integral to human salvation.
Gregory of Nazianzus (329-390) was another early Father who helped in shaping the church’s doctrine of Christ and the Trinity. He wrote of Jesus:
He is called man, not only that through his body he may be apprehended by embodied creatures, whereas otherwise this would be impossible because of his incomprehensible nature; but also that by himself he may sanctify humanity, and be as it were a leaven to the whole lump; and by uniting to himself that which was condemned may release it from all condemnation, becoming for all men all things we are, except sin – body, soul, mind. (Theological Oration IV.21)
Like Irenaeus, Gregory believed that in some sense the incarnation was restorative for human nature. God, by uniting humanity to himself, was making it possible for fallen mankind to be sanctified. In order to do this, Jesus had to fully embrace humanity. Since our whole nature had become corrupt through sin, all of it – body, soul, and mind – needed to be renewed. God the Word now has a human body, and soul, and mind, just like we do, because he became everything we are, save sin, so that he might save us from our sins!
The second non-negotiable is that God the Son became just like we are except for sin.
The greatest and most influential theologian of the Western church, Augustine (354-430), wrote a lot about Christ in his work On the Trinity:
And if I am asked how the incarnation itself was brought to pass, I reply that the Word of God itself was made flesh, that is, was made man, yet not turned and changed into that which was made; but so made, that there should be there not only the Word of God and the flesh of man, but also the rational soul of man, and that this whole should both be called God on account of God, and man on account of man. (IV.21)
In the Incarnation, God became what he was not without ever ceasing to be what he always was. He assumed humanity but always remained the eternal and divine Person, only now enfleshed!
The third non-negotiable is that in the Incarnation, God didn’t become something else in the sense that he ceased to be God.
Leo I (400-461) wrote what came to be called the “Tome of Leo,” which was very influential during the Council of Chalcedon (451). That council developed a confession which stated that the two natures of Christ joined together in one Person without being confused, changed, divided, or separated. Leo’s Tome stated,
While the distinctness of both natures and substances is preserved, and both meet in one Person, lowlines is assumed by majesty, weakness by power, mortality by eternity; and in order to pay the debt of our condition, the inviolable nature has been united to the passible, so that as the appropriate remedy for our ills, one and the same “Mediator between God and men, the man Christ Jesus,” might from one element be capable of dying, and from the other be incapable. Therefore, in the entire and perfect nature of very Man was born Very God, whole in what was his, whole in what was ours. (Leo’s Tomb 3)
This is similar to what another Father, Cyril of Alexandria (376-444), had to say: “Godhead is one thing, and manhood is another thing, considered in the perspective of their respective and intrinsic beings, but in the case of Christ they come together in a mysterious and incomprehensible union without confusion or change” (On the Unity of Christ).
The fourth non-negotiable is that the two natures joined in the incarnation are distinct yet united inseparably.
John of Damascus (675-749) was a Syrian monk whose Exposition on the Orthodox Faith is considered one of the greatest theological works of the Eastern Fathers. In it he wrote,
Now, when God the Word became incarnate, He did not assume His human nature as taken in a purely theoretical sense – for that would have been no real incarnation, but a fraudulent and fictitious one…For He assumed the first-fruits of our clay not as self-subsistent and having been an individual previously and as such taken on by Him, but as having its subsistence in His Person. Thus, this Person of the Word of God became Person to the flesh, and in this way ‘the Word was made flesh, and that without any change, and the flesh without transformation was made Word, and God was made man. (Orthodox Faith III.11)
The Word Incarnate has a human and a divine nature, but he isn’t a human and divine Person. In the Incarnation, the Divine Second Person of the Trinity assumed humanity in such a way that the humanity subsisted in the Person of God the Word. This is important because, if God the Son assumed a human person (as opposed to humanity in general), you would have two different persons accomplishing salvation. According to the teaching of Scripture and the ancient church, in the Incarnation the Divine Person takes human nature to himself.
The fifth non-negotiable is that One Divine Person, the Eternal Word, is the subject of the Incarnation.
You might be thinking, “Goodness! This all seems so obscure and impractical.” For the men above, this doctrine was deep (and difficult), but it wasn’t impractical. For them it was a matter of the most personal question any of us could have, “how am I right with God?” They recognized that due to sin, mankind was separated from God. They understood that we couldn’t through our own efforts restore ourselves and ascend to God, so we needed a Divine Savior. In the Incarnation, God united in Himself that which had grown distant: the divine and the human. By coming and taking human flesh, the Word was enabled to suffer and die in that flesh for our sakes, and when he rose from the dead, he lifted up all those who are united to him by faith and seated them with him (Eph. 2:6). During this season of the incarnation, may we all stand in wonder at the mystery of the Word Incarnate, the divine clothed in human frailty for us and for our salvation.