God has arranged things so that we do not know with precision the two most important dates in history: the birth of His Son, our Lord Jesus Christ, in Bethlehem, and His death on Calvary near Jerusalem.
Christmas is originally a Western feast. It first appeared in Rome during the first half of the 4th century, already fixed on December 25. That same date was the Natalis (Solis) Invicti—the Birth of the Unconquered (Sun), a feast for the divinized sun, connected to the Roman emperor. Christmas is the Christian transformation of this feast, very much in line with the syncretic and conciliatory spirit of Emperor Constantine the Great.
It is easy to see how Christians, by adopting this date and giving it a completely new meaning, also embraced “light” as one of the central liturgical themes: Christ, the true light, the sun that came from heaven to shine on the earth, just as the physical sun, visible to our eyes, begins to grow again at the winter solstice in these days of December.
Christmas is the Western counterpart to the older Eastern feast of Epiphany. At first, the Church celebrated Christmas—as it did Epiphany—as the manifestation of the Word of God to humanity. This is clear, for instance, in how often the liturgy for these days uses the words appareo (“to appear”) and related terms. When the West, in the same 4th century, adopted the Epiphany, the themes began to separate.
Shaped in an age marked by strong opposition to Arianism, the Christmas liturgy especially highlights the divinity of the Child of Bethlehem, while at the same time presenting Him as the true King or Emperor of the universe, the King of peace. These ideas give the Christmas texts a remarkably sublime tone, and they remain among the finest in the Roman liturgical books.
From the Middle Ages onward, however, in the West another emphasis gradually took root outside of the liturgy: the tender, moving image of Bethlehem’s manger scene. This helped Christmas become the most familiar and intimate of feasts.
