There was an interesting report on NPR that adds support to the idea that Americans, while religious, are not as religious as cracked up to be.
Much of the evidence for religiosity comes from surveys about the frequency of church attendance and the like, but the report quotes Philip Brenner, a professor of sociology at the University of Massachusetts in Boston, who says that when people are asked a question about how often they attend church, they actually answer a slightly different question, such as “Are you the sort of person who attends?” If they think they should be that sort of person, then they inflate their attendance. But when they are asked to keep a diary of how they actually spend their time, Sunday church attendance figures drop from the self-reported 45% to about 24%, not that different from godless Europe.
Interestingly, when people in Europe are asked to keep a time diary, their self-reports of frequency of church attendance is similar to that obtained from their time diaries.
So when people say that Americans are more religious than Europe, all that it might mean is that Americans feel a greater pressure to look like they are religious.