This post from Bay of Fundie is the best thing I've read on the Christmas-is-under-attack-myth-that-won't-die in a long time, and it links to Austin Cline's "War on Christmas" propaganda posters. It's worth keeping BoF's sentiment in mind as we head into another contentious holiday season:
There is no war on Christmas. People say "happy holidays" because there is more than one holiday at the end of the year. There's Christmas, Solstice, Hanukkah, Kwanzaa, and even Festivus. Pardon me for trying to be inclusive! [...]
Most of the time, the person saying "happy holidays" has nothing but the best of intentions. He's being sensitive to your feelings! He doesn't want to make presumptions about you or make you feel marginalized. He's trying to send the signal that it doesn't matter who you are or what you are, your value in society is as great as anyone else's. That it doesn't matter whether you are a member of the majority religion or not, you're welcome in America too. If that offends you, it says a lot more about you than it does about the well-wisher.
Those who proudly proclaim their lack of knowledge of--or interest in--"foreign" holidays are essentially saying that only their tribe's rituals are important, that only their clan's traditions deserve recognition, that only their kin's opinions are worth considering. We are ill-served by such parochialism in a steadily shrinking world.
Whether or not you celebrate Thanksgiving, I'd like to wish you all happy holidays!