The Feast of the Nativity: It’s Origin as a Holy Day
Contrary to popular belief and practice, Christmas [i.e., the celebration of the birth of Christ] is a Christian holiday [holy day] and derives from the ancient practice of the Orthodox Catholic Church. The word "Christmas" stems from the Old English usage of "Christes Maesse," which means "the Mass of Christ." It refers to the Christian celebration of the Mass on the Feast of the Nativity, held annually on 25 December since the 4th century.
Christians didn't always celebrate Christmas, per se, and there is no mention in the New Testament of such a feast day. This fact, however, should not prevent Christians from celebrating this important holy day. Indeed, the development of the date in Christian usage is the natural consequence of Christians remembering and celebrating our Lord's birth.
The earliest celebration of a Christmas-like theme in ancient and undivided Christianity was the celebration of the Feast of Epiphany [which means "manifestation"]. As early as the end of the 2nd century, Christians in the eastern portion of the Church began celebrating the Nativity
[birth] and baptism of Christ on 6 January. Associated with this celebration was the notion of the manifestation of Christ as God Incarnate; hence it developed the name of "Epiphany." This celebration slowly spread in usage to other areas of the Church, including the West.
In the late 3rd century, the Roman emperor Aurelian, a pagan, instituted the celebration the Festival of the Invincible Sun on 25 December. This was the date marking the beginning of the lengthening of the days; thus, there was the association of the sun being "born" to new life.
Christianity became legalized under Emperor Constantine in 314 A.D.; it was not long afterward, that the first celebration of the Nativity on 25 December took place. This first happened in the Western portion of the undivided Church. In order to combat the influence of the Feast of the Sun instituted by emperor Aurelian, the Church separated the Nativity from Epiphany and moved its commemoration to 25 December. Thus, the festival of the Invincible Sun became the "Birth of the Son of Righteousness." Since the worship of the Church was the singing of the Mass or Divine Liturgy, the December 25 celebration assumed the name of "Christ Mass," and the yearly Christian event which we call Christmas was born.
In addition to this, there was added to the Nativity celebration a pre-festival period of six weeks which were devoted to the preparation of those catechumens who would be baptized into the Faith at the Nativity service. This six week period had a spiritual connotation similar to the Lenten preparation and came to be called, “Advent,” which in Latin means “coming.” In some quarters of the Orthodox Church it is called “Advent-Lent.” In time, the Western Orthodox tradition shortened this season to four weeks; however, the Eastern Orthodox practice still uses the original six-week preparation.
Interesting asides to this story are these: the period between Christmas and Epiphany, which is considered a time of celebration, is 12 days and is called Nativitytide or Christmastide; thus we have the 12 days of Christmas. The hymn “O Come Emmanuel” is an Advent hymn, not a Christmas hymn, and its lyrics were originally the antiphons of the Vesperal hymn “Magnificat” which was sung each evening of the eight days prior to Nativity. The story of the three kings or Wise Men is part of the Epiphany celebration and commemorates the “manifestation” of Christ to the Gentiles. Thus, the hymn "We Three Kings" is not, contrary to popular belief, a Christmas hymn.
The concept of "Santa Claus" is an aberration of St. Nicholas, the patron Saint of Children in the Western Orthodox tradition [this great man actually existed and his feast day is 6 December]. The association of feasting and fellowship with Christmas probably derives from European Christian practices. However, it is generally believed that the practices of merrymaking and gift giving originate from the ancient pagan Roman festival, as do the uses of greenery and lights.
Consequently, when one celebrates Christmas as a Christian, he is following a practice introduced by the ancient Orthodox Catholic Church.