When I was in choir, I enjoyed singing songs with the phrase "Kyrie elison" and I love listening to Gregorian chants, but I do so from the artistic point of view. Christmas carols are another thing, but I have to say my favorite Christmas carol these days, aside from "Do They Know it's Christmas?" by Band-Aid is "White Wine in the Sun" by Tim Minchin.

It really depend on where, when and why. Like a lot of art, much of our great musical pieces where written to please the Church, not secular man. They were meant to inspire one to a religious life. Yet we look at the great masterpieces without questioning our non-belief, why not the same with classical music. If sung as part of a classical art series, even during the winter holiday season, listening and singing is a joyous thing. I draw the line when it comes to singing in an organized religious service.

If you enjoy it,that is all that matters.

Are the other members aware of your atheism? If so and they don't care i wouldn't worry about it.

I feel the proper Christian response should be delight that even though you aren't faithful you lend your abilities to something that might mean something to someone that is.

If they don't and it would bother them that's an unfortunate and sticky situation and the answer is more of a...cluster of potential outcomes. Maybe they value having a choir member they can count on, maybe they believe that strongly in camerderie, maybe they get mad.

Plus, even they know Santa is fake??

I don't think so.

I'm a stone cold atheist, and I personally believe that one of the most awful times of the year is the run up to the Christmas holiday.

However, one of my most favorite pieces of music in the whole wide world is John Rutter's "What Sweeter Music", which is a Christmas carol.