very few people do it because of real belief [...] beliefs never came into question. They were not exactly expected to think

I think LW participants are probably much more troubled than the average about making public declarations that they believe something that they don't actually believe. (I'm not sure I have very good reason for this, beyond the fact that I'm fairly sure it's true of me and it seems handwavily like I'm fairly typical of LWers in this area.)

So if people here -- or others who resemble people here -- are more worked up about (ir)religion than you expect, this may be part of why: the attitude you describe that would make it easier not to get worked up doesn't come naturally to those people.