For Catholics, the Orthodox and mainstream denominations like Lutherans and Epsicopalians/Anglicans, much of our theology and Scriptural exegesis comes from the Church Fathers. These, broadly speaking, were theologians, mostly they were priests and bishops, who, mostly, lived before the canon of the Bible was decided and whose sermons and lectures give us insight into how the Early Church interpreted Old Testament scripture as well as the books that later became the New Testatment. One group, called the Apostolic Fathers are significant because they were disciples of the original Twelve and their writings reflect Christianity as the Apostles taught it.
The Church Fathers were very much into Christmas as a holiday celebrating the Nativity. Here is a sampling from their sermons.
St. Leo the Great (400 – 10 November 461)
Our Saviour, dearly-beloved, was born today: let us be glad. For there is no proper place for sadness, when we keep the birthday of the Life, which destroys the fear of mortality and brings to us the joy of promised eternity. No one is kept from sharing in this happiness. There is for all one common measure of joy, because as our Lord the destroyer of sin and death finds none free from charge, so is He come to free us all. Let the saint exult in that he draws near to victory. Let the sinner be glad in that he is invited to pardon. Let the gentile take courage in that he is called to life. For the Son of God in the fullness of time which the inscrutable depth of the Divine counsel has determined, has taken on him the nature of man, thereby to reconcile it to its Author: in order that the inventor of death, the devil, might be conquered through that (nature) which he had conquered.
St. Gregory of Nazianzus (329 – 25 January 390)
This is our present Festival; it is this which we are celebrating today, the Coming of God to Man, that we might go forth, or rather (for this is the more proper expression) that we might go back to God – that putting off of the old man, we might put on the new; and that as we died in Adam, so we might live in Christ, being born with Christ and crucified with Him and buried with Him and rising with Him. For I must undergo the beautiful conversion, and as the painful succeeded the more blissful, so must the more blissful come out of the painful. For where sin abounded grace did much more abound; and if a taste condemned us, how much more does the passion of Christ justify us? Therefore let us keep the Feast, not after the manner of a heathen festival, but after a godly sort; not after the way of the world, but in a fashion above the world; not as our own, but as belonging to Him who is ours, or rather as our master’s; not as of weakness, but as of healing; not as of creation, but of re-creation.
St. Augustine of Hippo (13 November 354 – 28 August 430)
Wake up, O human being! For it was for you that God was made man. Rise up and realize it was all for you. Eternal death would have awaited you had He not been born in time. Never would you be freed from your sinful flesh had He not taken to Himself the likeness of sinful flesh. Everlasting would be your misery had He not performed this act of mercy. You would not have come to life again had He not come to die your death. You would have perished had He not come.
St. John Chrysostom (349 – 14 September 407)
Come, then, let us observe the Feast. Truly wondrous is the whole chronicle of the Nativity. For this day the ancient slavery is ended, the devil confounded, the demons take to flight, the power of death is broken, paradise is unlocked, the curse is taken away, sin is removed from us, error driven out, truth has been brought back, the speech of kindliness diffused, and spreads on every side, a heavenly way of life has been ‘in planted on the earth, angels communicate with men without fear, and men now hold speech with angels.
And just because one can never have too much St. John Chrysostom:
Behold on Christmas a new and wondrous reality. The angels sing and the archangels blend their voices in harmony. The Cherubim hymn their joyful praise. The Seraphim exalt Christ’s glory. All join to praise this holy feast, beholding the Godhead here on earth and man in heaven. He Who is above now for our redemption dwells here below, and we who are lowly are by divine mercy raised up. Bethlehem this day resembles heaven, hearing from the stars the singing of angelic voices. Ask not how. For where God wills, nature yields. For He willed. He had the power. He descended. He redeemed. All things move in obedience to God. This day He Who is born and He Who is becomes what He is not. He is God become man, yet not departing from His Godhead.