This year Andrew Jones beat me to it, nicely:
Not every believer will come up with the same list of holy days. "One person regards one day as holier than other days, and another regards them all alike. Each must be fully convinced in his own mind" Romans 14:5
So, if your conviction is to celebrate Christmas, by all means put on that party hat, decorate that tree and roast that turkey but don't push that particular conviction on to other believers lest you become a stumbling block. "Therefore do not pass judgment on one another, but rather determine never to place an obstacle or a trap before a brother or sister." Romans 14:13.
And if God's good people are giving you hell because of your Christmas tree, and if you are convinced in your own mind that you are celebrating Christmas to the glory of God, then stick up for what you believe. "Therefore do not let what you consider good be spoken of as evil. For the kingdom of God does not consist of food and drink, but righteousness, peace, and joy in the Holy Spirit." Romans 14:16-17
And in sticking up for what you believe, give them some space for what they believe also.
Check out his whole post, here.