Actually, I find it rather more interesting that you consider religion as something which people actually sit down and think about. Whilst I suspect that a lot of the people reading this (myself included) are the kind of people who actually would want to have a careful justification for their religious position, the fact that the vast majority of the world follows (or at least claims to adhere to) the same religion as their parents tends to indicate fairly strongly otherwise.

Of course, the fact that this statistic also applies to my own smugly-enlightened atheism is something I'm not sure I could argue my way out of. I'd like to believe that my considerations of the issue have a fair degree of logic to them, but proving that it's not just worthless self-justification is non-trivial.

Hmm. I don't think I intended to suggest that everybody sat down and thought seriously about religion: only that some people eventually do, and people who haven't (or haven't yet) will tend to follow the religion in which they were raised because it's never occurred to them to consider alternatives. I'm not sure this contradicts you.