Shambles was right, this is most definitely a music thread. De-BS'd it
It's about people's habits (not all Catholic) regarding religious music.

I had a hard time for years singing religious music when I wasn't. I figured people might think I WAS religious. Then I realized I was giving up part of what was, in my case, my heritage. I was rejecting Christian hymns and gospel in a way I would never do if given the opportunity to sing along on a song of any other religion that wasn't hateful. I also realized I sang songs involving rape, murder, incest, sailing, whaling, yada-yada-yada, and none of these things were part of my life. With the possible exception of sailing, I didn't believe they were even good things. So I re-acquainted myself with gospel music and hymns.

Now, unless I'm at a religious event where fellow attendees have reason to believe everyone else there is a member of that religion, and I think they don't want non-believers singing, I'll join in. I'm not likely to be in this sort of situation though.