Well, I'm agnostic, but you can consider me an atheist in regard to an conceptual "god" model" I don't believe in afterlives or a cosmic purpose. But, given that, I still love Christmas. I grew up with an agnostic father and a secular Catholic mother. Christmas has never been about Jesus despite the name.
Christmas is an awesome way to combat the effects of winter; less sunlight, colder temperatures, death of crops and livestock. To be honest, Jesus really has little to do with the solstice traditions any more, just like 1000 years ago. So, as long as we all realize what it is, it's quite fun. Though I will give credit where it's due; many Christian Christmas songs are wonderful as well. Again, it's all about realization.