Voice from the Past - Athanasius

Perhaps you are wondering why, when we proposed to speak of the incarnation of the Word, we are now treating of the beginning of mankind. But this is not irrelevant to the purpose of our exposition. For we must, when speaking of the manifestation of the Saviour to us, speak also of the beginning of mankind, in order that you may know that our own cause was the reason of his coming, and that our own transgression called forth the mercy of the Word, so that the Lord came even to us and appeared among men. For we were the cause of his incarnation, and for salvation he had compassion to the extent of being born and revealed in a body.

Athanasius, 295-373 AD, The Incarnation of the Word, 4 (Contra Gentes and De Incarnatione, translated by Robert W. Thomson, Oxford at the Clarendon Press, 1971, p. 143)

Why is the idea of the Fall important to our understanding of salvation? What implications does it have for our life today?