Except that America does not follow the trend line, as I said. It stands alone against the tide. Maybe it's because the place is in and of itself, as much about a state of mind about possibilities as anything else.
I would say it is because of America's adversarial political relationship with opposing creeds: first atheist Communism and now Islam. The latter in particular, and the reaction to it (around the entire periphery), are the primary bulwarks of religious precept that endure. In those societies, religion still provides the necessary utilitarian function of harnessing collective action.