Every congregation has them -- the husband who comes to church a few times a year with his religious spouse, the college student who attends services when she is home to please her parents, the Baby Boomers who are uneasy with services they consider too liberal or too conservative.
They are part of a growing number of Americans with weakened ties to organized religion, many of whom will identify themselves in surveys as having no religious home.
What is up for debate is whether these new "nones" are a sign of an inevitable movement toward a more secular nation, or whether they represent shifts in the religious marketplace but stability in basic beliefs and behaviors.
There is no easy answer.
A growing body of evidence reveals a complex portrait of Americans who do not identify with a particular religious group. What research is increasingly showing is that "nones" are a dynamic group whose members cannot be simply characterized as either atheists or in other popular categories such as "unchurched believers" or "spiritual but not religious."
There are people who appear to be consistently secular in their beliefs. However, the nones also include a large group of people who switch their preferences over time, and continue to attend a particular congregation and express belief in God.
These individuals are "betwixt and between the religious and the secular, but they are not necessarily on the path to being one or the other," researchers Chaeyoon Lim of the University of Wisconsin-Madison, Carol Ann MacGregor of Princeton University and Robert Putnam of Harvard University said in the Journal for the Scientific Study of Religion. "They stand halfway in and halfway out of a certain religious identity."
By the numbers
The number of Americans expressing no religious affiliation has grown significantly in recent decades, according to several surveys.
The percentage of General Social Survey respondents reporting no religious affiliation more than doubled to 16.3 percent from 1990 to 2008. The American Religious Identification Survey found the percentage of respondents self-identifying as nones rose from 8 percent in 1990 to 15 percent in 2008.
But there also are indications the growth of nones is slowing down from the "secular boom" of the 1990s. The 2008 ARIS survey found some 1.3 million more American adults joined the ranks of the nones in the 1990s, while since 2001 the increase has dropped to some 660,000 a year.
And nones also are proving to be one of the most dynamic groups in terms of changing affiliations.
In the 2006-2007 Faith Matters Study, fewer than 70 percent of the respondents who said their religious affiliation were "nothing in particular" in the first wave reported the same preference when they were contacted a year later. That compared, for example, to 92 percent of Catholics who gave a consistent answer in both surveys.
What stayed largely the same, however, was the overall percentage of religious nones, and the basic beliefs and behaviors of those switching in and out of the none category. For example, only 2 percent of those switching into the "nothing in particular category" from other religious preferences said they had become less religious in 2007 than in 2006.
Predicting the future
The gray areas of religion many nones find themselves in make it difficult to predict the future.
In their journal article based in large part on data from the Faith Matters Study, Lim, MacGregor and Putnam said it seems reasonable to speculate that the limited religious identity of those nones who switched affiliations may fade away over time.
Other findings such as little change in religious service attendance, however, offer a different picture.
"Despite the instability in their reported religious preferences, their marginal involvement in religion appears to be enduring," the researchers wrote. "When they do experience religious changes, they do not necessarily head toward secularism."
Consider some other countervailing forces muddying future predictions:
Several other factors, from the clergy sex abuse scandal leading some away from churches to immigration and fertility rates that some say favor the religious population, also come into the picture.
Religious leaders and secularists, take note: The struggle for the hearts and minds of many in this diverse group of religiously unaffiliated Americans is far from over.
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