You're lucky. A lot of us have pagan liberal inlaws who ride this anti-Christian bandwagon.
Sometimes I wonder if these people are just rebelling against the social pressure that compels them to go out and fight the Christmas shopping crowds and do all the holiday decorations and such. They feel controlled by Christmas and they resent it.
But if you don't want to celebrate Christmas don't do it.
People were partying and feasting and singing and celebrating long before Jesus. I don’t get the problem. I celebrate Christmas and nobody has a problem with it. I don’t care what they do outside the town hall. I do what I want in my yard and say what I want to the people I care to greet. Seems to me that most of the stuff about the “war” on Christmas is overblown and silly. There is a war on but it’s not on Christmas as a time to celebrate the birth of Jesus and have a good time doing it.