There's a common meme that goes around about Christmas.
It starts when a Christian says, "You know, it's ridiculous for me who is a Christian to wish my friend who is a Christian 'Happy Holidays'; I would rather just say 'Merry Christmas!' to him or her. In fact, because *I* am a Christian, I'm going to say Merry Christmas to everyone because that's what I'm celebrating!"
Now, there is a problem with this. The Christian doesn't have any good way to identify people who aren't Christian straightaway.
But the real problem starts when one of those non-Christian people gets fed up at being joyously wished a happy celebration of a holiday that they just don't do. They respond, "But YOU STOLE CHRISTMAS."
The rationalization is that every single Christmas tradition that doesn't directly involve the Scriptures is taken from some other faith's traditions. But let's look at that phrasing.
When a woman gets married and decides to use her husband's last name as her own, is there anyone out there who could possibly refer to that as "stealing his name"? It's done by their mutual consent, when she takes something that she was not previously entitled to and adopts it as her own. But no one says that she stole it, they say she "took his name."
What about other situations? My grandmother had a necklace that was a gold tree set with the family's birthstones; when and if I inherit it, I plan to have our daughter's birthstone added (she didn't have time to do so before she died). Is this "stealing" her necklace? She's passed away, it's not like she could take it with her.
Given that a lot of Christian conversions happened because someone in the family converted and others chose to over time, I don't think it's unreasonable to say that a lot of a family's former religious tradition might have been carried over from year to year. And then, of course, other families they came in contact with might have picked up "a Christian way to celebrate with this tradition" and carried it on. Traditions that are rich with symbolism of other Gods may well be this way-- they weren't adopted in order to deceive, but were continued by people who had become Christian but didn't want to give up the traditions of their ancestors. It's much the same way that some pagans I've known put up Christmas trees because their families did so, or because they want a place to put their kid's presents, and then rationalize it by saying some other culture put up trees somewhere.
And in one final point, while we Christians don't own the season, you other people don't either. Winter came and went in the Northern Hemisphere during this part of the year for a long time before anybody blamed the Divine for it; I think it's ridiculous to claim that lighting candles against the great darkness, or feasting because the harvest is in, or even singing together against the cold, is specific to any particular faith.
I'd also like to mention that for those of us who take Christmas seriously and devoutly, the wide-flung accusations that we've committed a moral wrong by celebrating our own holiday are hurtful and mean. If you mean to say "those traditions aren't exclusive to you" then say so-- but saying that WE STOLE our traditions implies that we have no right to celebrate AT ALL.
If you believe that seeing Christians using traditions shared by other faiths is devaluing to those other faiths, would you please explain why?
Also, please explain how this situation differs from either:
a) Gay people getting married does not devalue the institution of heterosexual marriage
or
b) Whether or not I choose to keep firearms in my house is my personal business and not my neighbor's.