So I assume you don't celebrate Christmas at all? I'm an atheist, too, but this is a weird thing to get up in arms about.
I don't care for Xmas and have as little to do with it as I can. There are some family gatherings I feel obligated to attend because I don't want to hurt feelings, but that's about it. I don't think it's that weird to feel uncomfortable listening to people singing the praises of Jesus at the grocery store. I'm not up in arms about it though.
My grocery store has the SA ringers and I do not donate because of the anti-gay thing. I also really dislike the bell ringers because I have sensory issues, and that damned bell is like a drill in my skull.
This evening, when I went to the store, there were carolers next to the bell ringer. They were singing "Joy to the World". I'm not sure the carolers were affiliated with the bell ringer, but no matter. I'm an atheist. Being loudly told "HE RULES THE WORLD" while I'm simply trying to acquire my sustenance and sundries was very disconcerting.