Well, there's a theory that when the standard of living increases, religiosity decreases because people don't think they need it in their lives since they're mostly comfortable.
Well, off the cuff, there might be some sense in that. I think there'd be a whole lot of things feeding it, though.
1) Education. And no, I don't mean education leads to atheism. Personally, I think education leads to us being more likely to make our own choices. More likely to choose a religion/non-religion that is 'not the norm'.
2) Religious freedom. If I lived in Iran, for example, would I be an open atheist (which is kinda...well, it's a weird term, but anyways, you know what I mean, I guess). Maybe. Maybe not. If I took a hundred random atheists and put them in Iran, how many would be open? Take the same hundred and put them in New Zealand. I'm guessing more identifiable atheists.
3) Time. Sure, we're time poor in the West, or at least I am. But I have easy access to all sorts of information in seconds. I carry the internet in my pocket, I have all sortsa appliances and conveniences to help with dinner and washing, my car gets me around, etc.
Plus, when making some of my formative decisions on religion, I was a lazy uni student who could read political and religious books as a hobby, have debates over coffee with friends of various persuasions, and worked out my general philosophy on life.
I suspect a general philosophy on life is far less likely to challenge your parent's religious views when things like 'survival', 'food', 'medicine' are first and foremost.
4) There might be some truth to religiousity decreasing due to people not thinking they need it. Certainly some use religion as a crutch. But I've never been the least bit tempted to become religious even when faced with hardship. That includes not only the religion of my culture, my parents, etc, but other religions that would be less likely to clash with my atheism.
If I lived in Iran, perhaps I go to the Mosque and pray to Mecca. I'd hazard a guess that given equivalent access to education, freedom of speech, etc, I'd still be an atheist, even if I went to Mosque. But the scenario is impossible, really. If I was raised in Iran, my life experience would be different. Some (at least) of my thinking would be different.