The Incarnation of the Son of God
Thus does the Evangelist John announce the glad tidings and theologise in the first lines of his Gospel.
“In the beginning was the Word, and the Word was with God, and the Word was God. The same was in the beginning with God. All things were made by Him; and without Him was not anything made that was made… And the Word was made flesh, and dwelt among us…” (John 1:1-3,4)
The unutterable, unknowable, invisible, unattainable God, the Second Person of the Holy Trinity, became man in the form of the God-Man, the Lord Jesus Christ, and dwelt among men on earth.
The preaching of the God-Manhood of the incarnate Son of God constitutes the content of the words of the Saviour Himself, the content of the whole message of good tidings announced by the Apostles, the essence of the four Gospels and all of the Apostolic writings, the foundation of Christianity, and the foundation of the teaching of the Church.
“Great is the mystery of godliness; God was manifest in the flesh (I Tim.3:16)
Read more about the great Feast of Nativity:
Why did God became Man? The answer of Saint Athanasios the Great, here
The Symbolisms of the Orthodox Icon of Nativity, here
The Nativity Discourse of Saint Gregory the Wonderworker, here
The Gift of Christmas, here
On the Incarnation or becoming Man of the Son of God, here
The Orthodox Celebration of Christmas, here
The Nativity Sermon of Saint John Chrysostom, here
On the Nativity by Saint Leo the Great of Rome, here
The Christmas Sermon of Saint Gregory the Theologian, here
Christ is Born, Odes 1-8, mode 1. Chanted by “Romeiko Ensemble”, here