We have dealt as far as circumstances and our own understanding permit with the reason for His bodily manifestation. We have seen that to change the corruptible to incorruption was proper to none other than the Savior Himself, Who in the beginning made all things out of nothing; that only the Image of the Father could re-create the likeness of the Image in men, that none save our Lord Jesus Christ could give to mortals immortality, and that only the Word Who orders all things and is alone the Father’s true and sole-begotten Son could teach men about Him and abolish the worship of idols But beyond all this, there was a debt owing which must needs be paid; for, as I said before, all men were due to die. Here, then, is the second reason why the Word dwelt among us, namely that having proved His Godhead by His works, He might offer the sacrifice on behalf of all, surrendering His own temple to death in place of all, to settle man’s account with death and free him from the primal transgression. In the same act also He showed Himself mightier than death, displaying His own body incorruptible as the first-fruits of the resurrection.
You must not be surprised if we repeat ourselves in dealing with this subject. We are speaking of the good pleasure of God and of the things which He in His loving wisdom thought fit to do, and it is better to put the same thing in several ways than to run the risk of leaving something out. The body of the Word, then, being a real human body, in spite of its having been uniquely formed from a virgin, was of itself mortal and, like other bodies, liable to death. But the indwelling of the Word loosed it from this natural liability, so that corruption could not touch it. Thus it happened that two opposite marvels took place at once: the death of all was consummated in the Lord’s body; yet, because the Word was in it, death and corruption were in the same act utterly abolished. Death there had to be, and death for all, so that the due of all might be paid. Wherefore, the Word, as I said, being Himself incapable of death, assumed a mortal body, that He might offer it as His own in place of all, and suffering for the sake of all through His union with it, “might bring to nought Him that had the power of death, that is, the devil, and might deliver them who all their lifetime were enslaved by the fear of death” (Heb 2:14)
Have no fears then. Now that the common Savior of all has died on our behalf, we who believe in Christ no longer die, as men died aforetime, in fulfillment of the threat of the law. That condemnation has come to an end; and now that, by the grace of the resurrection, corruption has been banished and done away, we are loosed from our mortal bodies in God’s good time for each, so that we may obtain thereby a better resurrection. Like seeds cast into the earth, we do not perish in our dissolution, but like them shall rise again, death having been brought to nought by the grace of the Savior. That is why blessed Paul, through whom we all have surety of the resurrection, says: “This corruptible must put on incorruption and this mortal must put on immortality; but when this corruptible shall have put on incorruption and this mortal shall have put on immortality, then shall be brought to pass the saying that is written, ‘Death is swallowed up in victory. O Death, where is thy sting? O Grave, where is thy victory?” (1 Cor 15:53).
[St. Athanasius the Apostolic, On the Incarnation of the Word]