Fight back calmly and politely. But fight back. Do not be deterred by being a called a bigot. Wanting a Christmas party hardly makes you a bigot. It is the minority member who wants "Christmas" dropped who is the bigot. Furthermore few minority members actually do object. The vast majority of Jews, whether or not they celebrate Chanukah, honor Christmas, as do the vast majority of blacks, whether or not they celebrate Kwanzaa.
Demand a vote. It will smoke out the progressives' contempt for democracy. And ask why a Halloween party is permitted at the company. That will reveal the great American secret: Conservatives (such as Christians who do not celebrate Halloween) are usually far more tolerant of things they disagree with than their liberal opponents are.
And know that diversity professionals can support this. When I spoke on this subject at the national headquarters of Toyota, the company's head of diversity told me that he supported my call to rename the "holiday" party a Christmas party. I would love to give that talk at every company in America. As that is impossible, I am making the lecture available (on audio and video through my Web site, www.dennisprager.com). Furthermore I will publicize the name of every company where workers are attempting to bring back the name "Christmas" for their December party. Please let me know about your efforts. This is a fight worth making.
Do not be intimidated by anti-Christian animosity that masquerades as "sensitivity" or "inclusiveness." And when someone asks you whose idea it was, tell them it came from a Jew who doesn't observe Christmas, but who loves and honors the fact that the vast majority of his fellow Americans do.