1) Christmas as it's presently celebrated is not celebrated on the actual birthday of Joshua Ben Joseph of Nazareth. That would have been in the spring/early summer. Shepherds would not have sheep grazing at the start of a Palestinian winter. Christmas also is a holiday that has origins in the pagan calendar of Rome, with the Carnival-like holiday of Saturnalia, and which has folded in the also-pagan-but-different culture holiday of Yule, as well as elements of Germanic paganism. The day is celebrated on a Graeco-Roman holiday, the tree comes from the Heathens, and the term Yule from the Celts.
2) Christmas, at least in the United States was not celebrated until the mid-19th Century. The Puritans outlawed it and the original-generation Southerners were irreligious anyhow and didn't give a damn on the one hand or alternately were as puritanical as the Puritans on the other. We owe our modern concepts of Christmas to Charles Dickens, the famous writer of what a crapsack world Victorian times actually was. Christmas was outlawed by the Puritans and not practiced in early US culture, BTW, because it was considered too rowdy for a 'city on a Hill' to practice.
3) Christmas as per the 21st Century is a great ode to the commercialist/greedy/gluttonous tendencies of society. It's an excuse to shamelessly indulge in at least four of the Seven Deadly Sins and perhaps six (Sloth is not really possible to indulge in with all the shopping that the 'ideal consumer' would do unless they're Magnificent Bastards). This is completely unrelated to the tenets of Christianity, in any form, in any fashion. Those that take the Bible literally have no excuse, those that do not have even less.
4) Thus, the War on Christmas is an annoying meme fostered by a 24/7 cable channel run by Australians and Saudis that needs something to do on a slow news day and turns to kicking hornets' nests.
5) Happy Hanukkah to all Jews on T_P and also to those who aren't.
6) TL;DR: The War on Christmas is a bunch of nonsense so let's not hear about it like it actually means anything.