The following are some excerpts from the first two chapters of On the Incarnation by St. Athanasius.
Creation and the Fall (some excerpts)
"Now in dealing with these matters it is necessary first to recall what has already been said. You must understand why it is that the Word of the Father, so great and so high, has been made manifest in bodily form. He has not assumed a body as proper to His own nature, far from it, for as the Word He is without body. He has been manifested in a human body for this reason only, out of the love and goodness of His Father, for the salvation of us men. We will begin, then, with the creation of the world and with God its Maker, for the first fact that you must grasp is this: the renewal of creation has been wrought by the Self-same Word Who made it in the beginning. There is thus no inconsistency between creation and salvation for the One Father has employed the same Agent for both works, effecting the salvation of the world through the same Word Who made it in the beginning."
"You may be wondering why we are discussing the origin of men when we set out to talk about the Word’s becoming Man. The former subject is relevant to the latter for this reason: it was our sorry case that caused the Word to come down, our transgression that called out His love for us, so that He made haste to help us and to appear among us. It is we who were the cause of His taking human form, and for our salvation that in His great love He was both born and manifested in a human body. For God had made man thus (that is, as an embodied spirit), and had willed that he should remain in incorruption. But men, having turned from the contemplation of God to evil of their own devising, had come inevitably under the law of death. Instead of remaining in the state in which God had created them, they were in process of becoming corrupted entirely, and death had them completely under its dominion. For the transgression of the commandment was making them turn back again according to their nature; and as they had at the beginning come into being out of non-existence, so were they now on the way to returning, through corruption, to non-existence again."
The Divine Dilemma and its Solution in the Incarnation (some excerpts)
"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."
"For naturally, since the Word of God was above all, when He offered His own temple and bodily instrument as a substitute for the life of all, He fulfilled in death all that was required. Naturally also, through this union of the immortal Son of God with our human nature, all men were clothed with incorruption in the promise of the resurrection. For the solidarity of mankind is such that, by virtue of the Word’s indwelling in a single human body, the corruption which goes with death has lost its power over all."