A "christmas card" doesn't have to imply a religious preference. I have (that I know of) Jewish, Catholic, Shinto, Muslim, Atheist, Christian, Jehovahs Witness, Buddhist, Hindu, Mormon, Mennonite, and Wiccan residents in my building. Over the years, at least a few members of most of these belief sets have told me they enjoy the holiday card, gifts and attention. I would never have guessed that celebrating a commercial holiday would be offensive to anyone. Thank you for letting us know that it can be. That being said, I know it's possible to behave in a welcoming manner to customers who are different than me.
The cards I give out are very tasteful art on the front that was drawn by a friend. Inside it says "Season's Greetings" and thanks for choosing our community as your home, etc., signed by all the staff. Even the little ornaments that I gave out were just little resin snowmen, gingerbread house, etc.
Even though my little goodies are insignificant, my residents know that I took the time to personally make and sign each card, buy the treats, assemble the bags, and distribute them.
Forming connections like this has had a major impact on my turnover. It has decreased from 65% to 35% in the last 3 years. One downside is that residents are less "polite" because they know I will still care about them tomorrow even if they get upset with me today.
I remember feeling offended once during unit inspections when I came across a shrine to a very well known terrorist in a residents home office. But it was his home and he decorated it to his own preferences. If my office was in my home, I think I should have the right to display decorations that represent my beliefs. So fair housing could come into play. But if the office is separate and privately owned, it would be inappropriate.
Since our community is actually a privately owned business, we don't have free speech in the office. We never ever display or mention anything religious, even when not around prospects or residents. My Muslim residents are not offended by me wearing sleeveless tops, so I'm surprised that an atheist would be offended if I wore a small pendant shaped like a cross. Hopefully no one is offended by the Halloween candy dish on my desk.