A panel of expert on survey research on US religion, assembled earlier this month by the Pew Research Center, offers some of the clearest explication I have seen of the "nones." A transcript of that panel is now available. The take-away: the rise of the "nones" isn't nothing, but it is less significant than has commonly been understood. Religious practices, beliefs and values have more or less remained constant in the last 40 years. The percentages of people who say that religion is very important to them have remained more or less constant. The percentages of people who say that religion isn't important in their lives have also remained pretty steady.
What's changed is self-identification. That is, it's easier now to say one is not religiously affiliated.
Alternatively, it's harder now to say one is religiously affiliated.
The people who say they have no religion in particular are acting in the same ways they have always acted. They didn't used to go to church, and they don't now. They're somewhat religious, and always have been.
Rates of religiousness haven't really changed: it's just that there's now a new, perhaps clearer, way for one segment of the American population to describe themselves.
Frank Newport, of Gallup, clarifies that the social change being measured is a change in identification, which is separate and distinct from other forms of religiousness:
keep in mind that we're talking about, in religious identification, one measure of religiosity, but it is not necessarily correlated with or the same as many other possible measures of religiosity. We're talking about a self label in a question in a survey, which is, 'What is your religious identity?' ..... We're talking about one question where the respondent is asked to choose among those labels to self-report for themselves to a survey interviewer, and although all the other questions of religiosity that we measure in a survey context are also self-reports, they can be different, because some of them were asking a respondent to self-report on past behavior, most notably, church attendance; others were asking respondents to access cognitive states like importance of religion; and then there is another series of measures .... of belief in various aspects of religion, which are the same thing, asking people to assess what’s going on up in the brain. But when we asked religious identity, in some ways it’s different because we're asking people to publicly put a label on themselves in a given arena, and I think that there -- and that's what I want to talk about here, is that part of what we may be seeing here is a change in the way that people choose to label themselves, rather than something which represents a more fundamental change in some of the other measures of religiosity that we can look at.According to Newport, if one looks at the percentage of people who say that religion is important in their daily lives, and the percentage of people who say it's not, very little has changed. The religiousness and irreligiousness of Americans, measured in this way, has been basically constant, even while there's been this much noted shift in self-identified religious affiliation.
He explains, "it can be hypothesized that these people for whom religion wasn’t important now feel freer to tell a survey interviewer that they don’t have a religious identity."
The group that is now identifying as "none" is the group that never went to church, never thought religion was important, etc. Those who were only nominally affiliated with religious groups have begun to mark a different box on social surveys.
This explains, among other things, why the rise of the religious unaffiliated isn't exactly visible in church pews. Rates of church attendance haven't dramatically declined and have even increased in exactly the same period that rates of people describing themselves as "none" have shot up significantly.
As Greg Smith of Pew explains:
I've talked to religious leaders over the years, some of whom have said, 'How do I reconcile the growth in the 'nones' with the fact that my congregation isn't shrinking? There aren’t people who are leaving my congregation.' The answer is that the growth in the 'nones' is being driven by people who weren't there to begin with. So it's not to suggest that nobody among the ranks of the 'nones' will become religious or join a religious organization, but I do think that we shouldn't assume -- as is sometimes done -- that these are necessarily losses or that these are people that are just waiting to be activated. They may become activated, but I don't -- it's not so easy as just recapturing people [the churches have] lost.Claude Fischer of University of California Berkeley notes that levels of religious involvement peaked in the '50s, but "over two centuries, both membership and activity have in net increased .... religious involvement is still higher than it was a century ago."