Why do they celebrate Christmas at Hogwarts?

I've been sick with the flu for a week, and while I debated posting a deep spiritual awakening that I experienced... well, I figured I'd start with something a little more light-hearted. Especially since I still feel like my cerebrospinal fluid is solidifying and threatening to cause my skull to explode. (In other words, I still have a pretty bad headache.)

So, on with our post. With all due respect to Ms. Rowling, who I'm sure was less concerned with historical accuracy than with relevance for her audience, but wouldn't it be more appropriate for a castle full of witches and wizards to celebrate Winter Solstice and Spring Equinox? Those were, after all, the original pagan celebrations of the seasons. But more disturbing is the fact that Christmas is a celebration of the birth of Christianity, which was responsible for eradicating anyone who was suspected of magical affiliation, i.e. our lovable young Harry and his delightful little friends, they would have all been mercilessly burned at the stake, their homes and families destroyed by the agents of the religion who's holiday they are celebrating. (sorry for the gruesome imagery, it's the CFS...;-)

Don't get me wrong, Jewish law also deals severely with Jews who dabble in magical arenas, but since the Harry Potter books make no reference to Judaism - except maybe to insinuate that all good Jews practice dentistry... well, anyway, we're just going to keep us out of this particular conversation.

In the meantime, to all you magical beings out there, you should know that I am peeved on your behalf.