First of all, it wasn’t called Christmas. That name didn’t come into usage until the 11th century, when someone mentioned “Christ’s Mass,” but in Old English. Instead the day was more definitively, if probably inaccurately, referred to as “the Lord’s birthday.”1.King renders this more accurately than Scholz, who uses “Christmas.” While the Bible has nothing to say about the date in question, in the 4th century the church had decided on December 25 as Christ’s birthday.
I am sure everyone with an interest in ancient and/or religious history has heard how the church co-opted pagan festivals, places, and rituals to reinforce Christian doctrine. Even without the scholarly backup, it seems inconceivable to me that Christmas was not originally a solstice festival. I certainly wait for the days to start getting longer again, and I have electric lights! The church could make the solstice celebration a holiday (holy day), and the populace would continue to enjoy their mid-winter festival, but with a new focus. They could continue to celebrate the fact that the days would be getting longer (Paris gets only just over eight hours of daylight on the solstice, assuming it’s not too cloudy), as long as they also attended Christ’s mass.
As the centuries wore on more holy days and feasts were added to the Christmas ‘season.’ This made sense both practically and spiritually. Since the days were short and cold, not much work could be accomplished in any case, so you might as well make the best of it. Mid-December has always signified the re-birth of the season, as the sun shines longer, and it made sense to align the celebrations of this season with Easter, just three or so months away.
January 6 was added to celebrate the Epiphany, when John baptized Jesus. Feasts for Stephen (first martyr) and John the Evangelist were added on December 26 and 27, and some others as well. Here’s what happened in our period:
In 567CE the Council of Tours established that the time period between the feast of Nativity and Epiphany be celebrated as one festal cycle. The addition, in the eighth century, of the feast of Christ’s circumcision (January 1) incorporated the ancient festive tradition of celebrating the New Year. Whereas the Eastern Christian lands placed more emphasis on the celebration of Easter, the celebration of the 12 days between Christmas and Epiphany became the major focus of the peoples in northern and central Europe. For the peasantry, this Christmas season marked their longest extended vacation, since during the Twelve Days they generally were exempt from work.2.Lindahl et al, Medieval Folklore, pp77-79, have more to say on the evolution of Christmas.
So enjoy your time off this season! It’s a tradition more than a thousand years in the making.