[emn13]

...and easily defensible borders for when things did go pearshaped, and peaceful (and weak) neighbors to avoid the drain of constant defense, and had lots of internal cultures to draw from. And in any case throughout certainly the first half the 20th century the US was not uniquely religious; much of europe was too, and non-coincidentally shared the same faiths. The ascent of the US appears to have occurred at least somewhat before the loss of faith in europe.

So... who knows? I mean, there are so many differences you're never going to be able to pick the various effects apart without careful - but subjective and error-prone - plain old reasoning.

I don't see any particular reason to believe religion played a very notable role, but I don't think it's an absurd notion either: I just don't know, and haven't seen a very convincing argument either way.