Christmas isn't particularly Christian seeing as most of the people who celebrate it these days aren't Christians. It was Pagan to begin with anyway, it's the Winter Solstice that's what it is. You can take it as symbolic for the coming light of the salvation of Christ through the darkness of sin and ignorance if you want to put a religious spin on it. Jesus almost certainly wasn't born on 25th of December but seeing as we don't know when he was born you can use it as his birthday if you like. If you're an atheist you can enjoy good old fashioned Christian coming together of the family, you get a bit of Christian values through your backdoor.
Come all ye faithful joyful and triumphant.