So how did we end up celebrating a wintry white Christmas? The church only settled on a Dec. 25 Christmas in the fourth century. The standard explanation is that the early church conflated its celebration of the Nativity with pre-existing pagan festivals. Romans had their Saturnalia, the ancient winter festival, and northern European people had their own solstice traditions. Among the features: parties, gift-giving, dwellings decorated with greenery.
The reasoning goes that the growing church, recognizing the popularity of the winter festivals, attached its own Christmas celebration to encourage the spread of Christianity. Business historian John Steele Gordon has described the December dating of the Nativity as a kind of ancient-world marketing ploy.
But some put forward another, less well-known explanation for the Dec. 25 date - one with appeal for anyone uncomfortable with a connection between Christmas and the old solstice festivals. According to some scholars, Christmas was set near the winter solstice not because of any pagan traditions but based on a series of arcane calendrical computations. This argument hinges on an ancient Jewish tradition that had the great prophets dying on the same dates as their birth or, alternatively, their conception. Thus, to follow this peculiar assumption, the first step in dating Jesus' birth would be to date his death, which the Gospels say happened at Passover. The early Christian writer Tertullian calculated that the date given for Jesus' death in John's Gospel corresponds to March 25 in the Roman calendar. Many Christian churches came to celebrate the Feast of the Annunciation, marking the angel Gabriel's visit to the Virgin Mary to tell her that she would become the mother of Jesus, on this date. Adding nine months to this date produces a Dec. 25 Christmas.
This alternative explanation is sometimes deployed to dismiss the notion that the holiday had pagan roots. In a 2003 article in the journal Touchstone, for example, historian William Tighe called the pagan origin of Christmas "a myth without historical substance." He argued at least one pagan festival, the Roman Natalis Solis Invictus, instituted by Emperor Aurelian on Dec. 25, 274, was introduced in response to the Christian observance. The pagan festival "was almost certainly an attempt to create a pagan alternative to a date that was already of some significance to Roman Christians." According to Tighe, the pagans co-opted the Christian holiday, not the other way around.