As to religiosity, it's an interesting, if squirrely point. My thinking is that religiosity itself is more a measure of how you want to be thought of in terms of 'religious beliefs' not necessarily what you actually practice. So the discrepancy between what people say to a pollster and what they practice on the surface, though interesting in its own righ, may not be especially relevant to my larger point that the US is an especially religious culture. The point that they are saying it (or feel compelled to say it based on cultural norms) probably indicates, at minimum, the strength of the religious culture in which they live. Certainly, the same poll taken in Europe would probably be in the low teens, I would suspect. Again, as much an indication of the culture norm as what folks actually practice.

On the other hand, I find this is very interesting and I hope it's true:

I can't be sure, but it seems that there is a new mindset emerging. The religious critics like Dawkins, Sam Harris and Daniel Dennett are starting to make it acceptable for people to acknowledge their unbelief. In addition with people like Dobson leaving the stage the religious are turning more to good works and away from politics. Having been promised social changes for 60 years (from abortion to sex education to gay marriage) and having seen none of these programs delivered in any meaningful way they are becoming disillusioned.

Finally the younger generation is much less religious than their parents. About 50% of the children of evangelicals drop out as adults, for Catholics the numbers may be even higher.