It's true we're not required to celebrate Jesus' birthday as Christians, but almost all Christians all over the world celebrate Christmas, in various ways in various cultures, because we love Jesus and want to honor Jesus' entire life. Just because something isn't required doesn't mean it's forbidden, and Christmas is a chance for Christians to pass on their values to their children through reading stories from the NT to them or explaining who is who in a nativity scene.
Many Christmas traditions do have pagan roots, and to be honest, I'm ok with that because it symbolizes the Christian faith replacing the old religions. To me personally I feel it honors my European heritage, in the sense of these traditions being developed by my ancestors, before they knew Christianity, and then changing the meanings of the traditions as they embraced the Christian faith. As long as you don't attach any evil or demonic meanings to most things, I don't think it has those meanings.
Take Halloween for example. You can dress up in a silly costume, have fun with your friends, and munch on candy. OR you can sacrifice an animal in a bizarre and painful ritual. The first one is obviously benign, the second one is strictly forbidden by Christian faith. I think most Christians are smart enough to know when the line would be crossed and I think most of these holidays that fundamentalists rail against are benign as long as the people celebrating them are good people who just want to have fun.