Christmas, as a celebration, has very little to do with Christianity. You will notice there are no dates in the Bible other than the mention of Quirinius, which would mean Jesus would have had to have been born in 4 BC. A lot of work has gone into trying to pin down a date, most commonly in one of the autumn months, in about 3 ad. However, as a feast, it was unremarkable, and certainly was not celebrated as a birthday but as a reflection on the incarnation, the indwelling of God within humanity.
Until 386, very little attention was paid to the nativity, except as a teaching about how the kingship of Jesus should not be mistaken for ideas about worldly power and dominance. In the 4th century, in an effort to either contain or modify the excesses of Saturnalia, a thoroughly repulsive Roman holiday, the pope of Rome declared Dec. 25th to be the date of Jesus’ birth. He encouraged the converts to meditate on the nativity rather than revel in the streets. At its worst, Christianity became corrupted by some of the less savoury behaviour of the season. Most of our Christmas customs are related to much older religions and have nothing to do with Christianity.
It would probably be helpful for Christian families to separate Christmas and its fun, from the feast of the incarnation, the feast of “Immanuel,” God-with-us. I think we can enjoy the fun of the holidays, Santa and presents, reindeer and feasts, without having to harmonize them with a religious tradition that is about simplicity, about connection to the natural world, and to the ordinary folks who are the beloved of the Divine. For us the feast of the incarnation is about discovering the indwelling spirit of the Holy One who connects us to the earth, to each other, and to a story about how we are becoming truly human.