before that I stopped sending out Christmas cards years ago. It wasn't a sudden stop, more of a gradual fade. It was my way of going green long before going green was in vogue. Of course now that I'm married, Nightingale has resurrected the tradition.
In the world today, Holiday Cards are the Politically Correct answer to sending someone a greeting without offending them. Non-specific Holiday Cards are nothing new. When I was growing up, we sent these too. Only it wasn't a "I don't want to offend you because I don't know what you celebrate or how strongly you feel about it" gesture.
If you got a Happy Holidays card back in the day, it was a personal indictment. We were admitting that either 1) we couldn't get our act together and get our Christmas cards out in time, or 2) we didn't expect a card from you and you surprised us when we received yours just too late to get one out by Dec 25th.
For a time we even handled those exceptions by sending out Happy New Year's cards. Except we quickly realized that if we couldn't get it together with a month's head start, we probably were not gonna get it done with small window between Xmas and NYE, especially since we had to rely on the Post Office.
I don't think of holiday cards as a way of taking Christ of out Christmas and I don't get offended when I get one. I'm probably more put off if someone simply send a card with no personal flair indicating the card was meant for me other than the name and address on the envelope it came in.
When I did send out cards, I made a conscious effort to send my Jewish friends either Hanukkah Card, or a Holiday Card but if I slipped up and send them a Christmas Card, they took it in the spirit it was intended.
Some people get bent out of shape that the Political Correctness movement has gotten out of hand. It has, but not in this case.
"As Roger Simon once wrote, another way to think of PC is CD -- common decency. It's common decency to use language that does not offend IF your sincere wish is not to offend." -- Eric Zorn from his comments on Change of Subject.
So if you wish to make a genuine acknowledgement to those who may not celebrate the same winter holiday as you and you don't wish to offend them through your reference, then you want to use a neutral term.
After all, isn't Peace on Earth the underlying theme of most of these winter holidays anyway?