There were no birthday parties in the annals of early Christians. No party favors or gift-giving. The deaths of notable people were considered more significant than people’s birthdays. It should come as no surprise that Easter became the first Christian festival celebrated in the early church. Why not? If Jesus didn’t rise from the dead, we wouldn’t be making such a big deal of his birth. The first record of Jesus’ birth date appears in a writing of Clement of Rome in AD 200. He mentioned two dates Christians had proposed: May 20 and April 19 and then put forward a date of his own, November 18. December 25 didn’t appear as Jesus’ birth date until the fourth century. Two dates were widely recognized by the mid-fourth century: December 25 by western Christians and January 6 by eastern Christians. December 25th prevailed for the majority of Christians and January 6th became known as the Feast of the Epiphany, commemorating the arrival of the magi to Bethlehem. The interval between the two dates became known as the twelve days of Christmas. There you have it!
By the sixth century, given that Christianity had become the state religion of the Roman Empire, Emperor Justus decreed Christmas as a national holiday. Since Christians were already worshiping on December 25, the tradition of commemorating Christmas Eve followed suit, no doubt because Luke’s gospel records the announcement of the Messiah’s birth “as shepherds were keeping watch over their flocks by night” (Luke 2.8).
One of the oldest Christmas Eve prayers is contained in a liturgy called The Gelasian Sacramentary. A copy of this liturgy, complete with elaborate illustrations, dating to AD 628-715, is archived in the Vatican. This liturgy begins with recommended prayers and readings from Christmas Eve to Pentecost. We join with believers past and present in praying: