The Christmas holiday cannot be adequately understood or recognized without understanding what is true to its central mystery: the Incarnation. This Christian doctrine is important to Christianity because without knowledge of both who Jesus Christ is and why we need Jesus Christ, there can be no complete understanding of the Gospel or the means to salvation. Described in the first gospel is evidence of the importance of knowing who Jesus Christ is. Based on a simple question that Jesus asks his disciples, in Matthew 16:13: "Whom men say that I am the Son of God", one can distinguish a Christian from a non-Christian and a heretic from a non-heretic. distinct. The attempt to answer the fundamental question: "Who is Jesus Christ?" and further: "Why do we need Jesus Christ?" it is important because it broadens and enriches our understanding of Jesus Christ and also directs our hearts to why we celebrate his birth during the Christmas season. There have been numerous writings that attempt to help us understand who and why we need Jesus Christ. One book in particular ranks among those that may be one of the most profound of all. C.S. Lewis writes in the preface to the book written by Athanasius, the great fourth-century bishop of Alexandria, that it is indeed a "masterpiece" and "is a picture of the Tree of Life." Athanasius offers an approach to the doctrine of the Incarnation, which attempts to defend the Christian faith in his treatise "The Incarnation of the Word of God". In this work he seeks to refute the heresy of that time period and periods to come and to explain why Jesus is the Christ. His approach to this doctrine provides a helpful scripture-based foundation for the importance of the incarnation. This...... middle of paper ...... had a mother; no woman can give birth to God. Cyril of Alexandria suggested that Nestorius was proposing that Jesus had two natures united in a purely moral union. After Nestorianism came Eutychianism. In the end Eutyches, summoned several times to the permanent Synod of Constantinople in 448, presented himself and declared his position, while Christ has two natures before the incarnation, after the incarnation there was only one. The result of the Synod was that Eutyches was deposed and excommunicated, and the doctrine of the one nature rejected. Works Cited Erickson, Millard J.. The Word Became Flesh. Grand Rapids, Michigan: Baker Book House, 1991.Fitzwater, PB. Because God became man. Chicago: The Bible Institute Colportage Ass'n., 1934. Gore, Charles. The Incarnation of the Son of God. London: J. Murray, 1891. Streatfeild, George Sidney. The incarnation. London: Longmans, Green, 1910.