LOL! Please! I had more than 12 years of learning the basics. And check your own sources. Christ is the son of God, and in the Catholic Church he is considered an aspect of the Trinity: The Father, the Son, and the Holy Spirit. Three gods for the price of one!
And CHRISTMAS is about celebrating the birth of Christ, even though from bliblical references he was probably born (if he existed at all) in the spring rather than the beginning of winter, and even though the timing for Christmas was set to coincide with the pagan solstice festivals, first as an effort to hide Christian celebrations amongst the pagan celebrations, and later to make it easier for those pagans to convert.
Besides which, the Xmas card comment was SARCASM!
And finally, the reason I don't believe in any god is because I have never seen anything even remotely resembling evidence for the existence of any supernatural beings. All I've ever heard, my whole life, is hearsay and speculation. And if there's one thing my good Catholic education taught me, it was to rely on evidence, not hearsay, to decide what's real or not.
So again I say, to you and to any others here who feel I'm wrong: show me the evidence!