I’m just going to keep adding things as I think of them, so darth_ender’s going to have to reply to an entire book by the time he can get around to it 😉
There’s a lack of cultural awareness you get from being raised atheist. I really thought Jesus was a bank until I was around 9 years old (because, you know, when I saw Jesus Saves on signs, it was reasonable to assume it also provided low-interest 30-year fixed mortgages). I once joked with a friend that we should make “Pop Culture Cliff’s Notes” for home-schooled kids and others who might feel left out of playground talk. I think I could have used that for religion–I never got any sort of “This is why we don’t believe in God”, or “This is what other people believe” talk from the parents. We just… didn’t. Atheism, God, rejection of God, etc, never really came up. I didn’t know there was a word for what we were. Christmas was just snowball fights and a tree. Other people went to church sometimes, sure, but I wasn’t sure what exactly happened in there and it must not have been very important because it never came up and it mostly just meant I had to wait until Sunday afternoon to play with the neighbors.
There’s also the issue of active vs. passive “passing”. Passively appearing Christian is one thing, happens all the time. Actively doing it is really awkward and I never liked it. As an atheist, you nevertheless end up going to churches–weddings, funerals, etc. You may even go to a regular service if you’re caught staying in the wrong person’s house on a holy day. What do you do? You could simply not participate, but depending on the context, that can be really obvious, makes it look like you’re trying to make a statement/make yourself the focus of events rather than the religious service. Or you could do the “imitate a Christian” thing, where you bow your head, kneel, move your lips and/or sing and basically do all the visible actions while privately examining the grain pattern of the pew in front of you. To me, that option seems profoundly disrespectful, and yet it’s still often the best choice, so it’s what I do. Christian pantomime. I hope I do it well, because if people knew I was just doing an impersonation, it could be mortifying.
And sometimes–and I don’t mean this as disrespectfully as it sounds–keeping a straight face can be hard. Sometimes you learn something wildly new about a religion that you had no idea about before. Sometimes it’s simply a shock and it’s really hard not to register that on your face. I knew next to nothing about Mormonism, and went via obligation to a regular Mormon service one day–and due to the gender separation of certain aspects, I was completely on my own! Nobody who knew I was atheist could warn me about what was coming up. Let me tell you, the Cliff’s Notes would have been a lifesaver there.