I hope y'all had a pleasant Christmas, or whichever celebration of the Winter Solstice you partake in. Back to the problems with the historicity of Christmas. Reason #1 was that Matthew's and Luke's birth stories are completely different and contradictory. Reason #2 was that, outside of Matthew and Luke, none of the earliest Christian writings say anything about Jesus' birth. Therefore, speculations about Jesus' birth seem to have been a relatively late development in the Jesus tradition, much later than the narrative of his death or collections of his sayings.
The third reason to be skeptical of the historicity of the Christmas story is that there was a well-established pattern in the ancient Roman world of telling stories about the auspicious beginnings of a great person's life. Visitations from divine messengers or dreams explaining the significance of the individual, unusual phenomena in the natural world, incidents involving the infant or child that foreshadow his or her later attributes or activities--all of these are the sorts of stock features that appeared in narratives about the Roman emperors, Alexander the Great, Plato, Apollonius of Tyana (a pagan miracle worker with some striking resemblances to Jesus), and so forth.
What does this mean for the birth stories in Matthew and Luke? Follow me below the jump.
Almost all of the narrative elements of the birth stories are these types of stock features. Angels tell the child's father and mother about his unusual parentage and later salvific activity. A star shines in the heavens. Mysterious foreigners come to worship him. A murderous king threatens him. The most impressive parallel is with Luke's story of Jesus in the Temple at age twelve, astonishing the scribes and priests with his unbelievable knowledge (Luke 2:41-52). Every ancient leader worth his salt would have revealed his future greatness during his childhood, much like George Washington chopping down his father's cherry tree--sorry if you didn't know that one was made up too!
If the stories of Jesus' birth are historical, then why do they have such impressive similarities to many other examples of ancient biographical literature? Are the stories about Jesus true, and those about Alexander the Great and the Emperor Augustus made up? That seems about as arbitrary as saying that the stories about Jesus were made up, and Alexander the Great really did the sorts of things that his later biographers said.