In an essay on Slate, Shankar Vedantam speculates on why Americans tend to overreport attendance at religious services:

Religion in America seems tied up with questions of identity in ways that are not the case in other industrialized countries. When you ask Americans about their religious beliefs, it’s like asking them whether they are good people, or asking whether they are patriots. They’ll say yes, even if they cheated on their taxes, bilked Medicare for unnecessary services, and evaded the draft. Asking people how often they attend church elicits answers about their identity—who people think they are or feel they ought to be, rather than what they actually believe and do.

Vedantam cites a range of sociological studies showing sizable disparities between reported and actual church attendance in the United States and suggests that these results cast doubt on the claim “that America has somehow resisted the secularizing trends that have swept other industrialized nations.”

But some sociologists—noting that Europeans tend, conversely, to under-report religious participation—have argued that these “secularizing trends” might similarly be connected with questions of identity and assumptions about what counts as “normal.” José Casanova has written:

Indeed, the most interesting issue sociologically is not the fact of progressive religious decline among the European population since the 1950s, but the fact that this decline is interpreted through the lenses of the secularisation paradigm and is therefore accompanied by a secularist self-understanding that interprets the decline as normal and progressive, that is, as a quasi-normative consequence of being a modern and enlightened European. We need to entertain seriously the proposition that secularisation became a self-fulfilling prophecy in Europe once large sectors of the population of western European societies, including the Christian churches, accepted the basic premises of the theory of secularisation: that secularisation is a teleological process of modern social change; that the more modern a society, the more secular it becomes; and that secularity is ‘a sign of the times.’