Athanasius was a Christian theologian, a Church Father, the chief defender of Trinitarianism against Arianism, and a noted Egyptian leader of the fourth century. He was born in the year 298 and died May 2, 373. His writing, On the Incarnation impacted C.S. Lewis, among many others, and specifically informed Lewis’s writing throughout his life. This excerpt from On the Incarnation begins to answer the question, “Why was the Incarnation needed?”
Man, who was created in God’s image and in his possession of reason reflected the very Word Himself, was disappearing, and the work of God was being undone. The law of death, which followed from the Transgression, prevailed upon us, and from it there was no escape. The thing that was happening was in truth both monstrous and unfitting. It would, of course, have been unthinkable that God should go back upon His word and that man, having transgressed, should not die; but it was equally monstrous that beings which once had shared the nature of the Word should perish and turn back again into non-existence through corruption. It was unworthy of the goodness of God that creatures made by Him should be brought to nothing through the deceit wrought upon man by the devil; and it was supremely unfitting that the work of God in mankind should disappear, either through their own negligence or through the deceit of evil spirits. As, then, the creatures whom He had created reasonable, like the Word, were in fact perishing, and such noble works were on the road to ruin, what then was God, being Good, to do? Was he to let corruption and death have their way with them? In that case, what was the use of having made them in the beginning? Surely it would have been better never to have been created at all than, having been created, to be neglected and perish; and, besides that, such indifference to the ruin of His own work before His very eyes would argue not goodness in God but limitation, and that far more than if He had never created men at all. It was impossible, therefore, that God should leave man to be carried off by corruption, because it would be unfitting and unworthy of Himself.
(On the Incarnation, §6, pgs. 31-32)