What if someone asks why you don’t believe in God? While it’s a somewhat rude question, and therefore somewhat abandoning any atmosphere of politeness, that’s not necessarily an excuse to be rude in your answer.
Yes, it’s rude to ask, because it’s a personal question, something people don’t generally talk about. Oversharing is a bit rude, and therefore so is inviting someone to overshare. But a person who asks why you don’t believe in God isn’t necessarily (or, indeed, probably) being deliberately rude, and they may be genuinely interested in deep discussion (the sort that leaves behind niceties like etiquette, not to be rude but to be serious).
So, in answering such a question, the issue is whether to answer in the manner of an intellectual debate or as a personal journey (what Christians call “testimony”). Either option allows you to be politely vague about your reasons/experiences, although talking about your experience is less likely to come across as confrontational.
But any way you slice it, explaining why you don’t believe what someone else believes, or how you used to believe it but don’t anymore, is likely to come across as some sort of criticism of that person’s belief.
If you explain yourself in a relatively non-confrontational way (e.g. “I just found religious answers less and less satisfying as I went along in life,” or “I was raised that way” or even “I’m still looking for evidence of some deity’s existence”), and your questioner still tries to take offense, you can politely explain that you’re only answering the question they themselves asked. If they didn’t want an explanation of why you found theism to be inadequate or illogical or just plain silly, they shouldn’t have raised the question in the first place.
BTW, my own best answer to the question is this: Either human psychology was created by an all-knowing, all-powerful, all-loving God, or said omni-max deity was created by human psychology. The more I learn about human psychology, the more the latter proposition makes sense.
(cartoon via Chris Madden)
Atheist Etiquette 
Posted by Sarah on October 10, 2009 at 5:30 pm
I enjoyed your answer. 🙂
Posted by Shannon on October 10, 2009 at 7:58 pm
I don’t think it’s a rude question if it’s asked by someone who is honestly interested. Maybe it’s the way it’s asked but if a friend of mine asked me this, I could see us just having a nice conversation about it.
Posted by brachinus on October 10, 2009 at 8:16 pm
If someone’s genuinely interested in your sex life, is it polite to ask about it?
Sex isn’t religion (if it were, I’m not sure I’d be an atheist!) but it’s still a personal subject. As I said, it’s not “rude” in the sense that insulting someone’s mother is rude, but it’s still a breach of politeness (in the same way that people who are friends, family or lovers routinely breach politeness because they’re more familiar with each other).
If someone’s a close friend, etiquette doesn’t (or shouldn’t) really enter into it. Friends are people you don’t have to be polite to. At least, that’s how I think of it.
Posted by Shannon on October 11, 2009 at 11:18 am
LOL! Well, I hardly think talking about religion is the same thing as discussing someone’s sex life 😉
I also disagree that you don’t have to be polite to friends, but maybe we’re not working on the same definition of “polite”? I think the reason I can have conversations on religion is that we’re polite in our discussion. We manage to disagree without being rude to each other. And with some friends that politeness ends up with us deciding we can’t talk about a certain subject (and it’s not always religion).
But sex? Nah. Not the same at all in my opinion.
Posted by Madge on October 26, 2009 at 8:30 am
When I reply, I say “mostly because there is no god”
I think it’s just the right amount of shocking and evasive to have people not want to ask me any further.