A study of why people change religious affiliations, released this week by the Pew Forum for Religion & Public Life, found that more than half of Americans have changed faiths in their lifetime. Sixteen percent of the population is not affiliated with a religion, according to the study, but many respondents said they had not found the right religion. Washington Post reporter Jacqueline L. Salmon interviewed one of the study’s researchers, John Green, senior fellow in religion and American politics at the Pew Forum. Here is an edited transcript.

Q:What does the survey say about us as a nation? That religion is now a supermarket for us: We pick one of this and one of that, and if we don’t like it, we go someplace else?

A:Certainly, Americans believe in choice — whether it is in politics or in goods and services or in religion. People look for the religious organization that serves their needs. Now, some of that change is no doubt because of life cycle changes: The spiritual needs of an 18-year-old are very different from the needs of a 60-year-old. But some of these choices may reflect the fact that it also could be because religious organizations are sometimes ineffective at meeting people’s spiritual needs. Our findings do suggest that the more successful religious organizations — those that maintain their numbers and recruit new members — are those that are especially attentive to their members’ needs.

A lot of people react negatively to this market model because people think of religion as being about eternal truths and about ultimate values. But the image of a marketplace is very useful in understanding American religion. When people make such religious choices, they may not be making them for light or trivial reasons. They’re really seeking fulfilling spiritual lives, and they have a lot of options in America to look for that kind of fulfillment.

What are the messages in these study results for religious leaders?

One is that there are a lot of options for their members. People can pick up and leave pretty easily. That puts some extra pressure on leaders to make sure that their organizations are meeting the needs of their members — that they are attuned to changes, that they understand that leaving is an option.

For people who are trying to run institutions, this produces a real challenge. Their congregations or denominations are always going to have a high degree of flux. There is always a lot of instability. But, on the flip side, it also suggests there is a lot of opportunity. Even among the unaffiliated, there are people who have spiritual needs and who are open to outreach if the organization can figure out how to do that and how to do that effectively.

From the point of view of religious leaders, you have good news, bad news. The good news is that a lot of people are not giving up on religion. The bad news is, there is a lot of things about religion they don’t like. They’ll leave, but they could be brought back to faith if they found the right organization.

Among the unaffiliated, two-thirds have changed faith at least twice in their lives. Those are real supermarket shoppers.

The unaffiliated are a good example of religious choice. Most have left their childhood faith. A significant percentage of the unaffiliated were not hostile to religious belief. In fact, they told us they just haven’t found the right religious organization. They might try out the Baptists for a while and may not like it and may try the Pentecostals for a while and then they try another group. People in the unaffiliated category were particularly given to multiple movements. We use that analogy of the marketplace. These are serial shoppers, and they just keep going. Perhaps at some point, they will find an affiliation that really works for them.

So it belies the idea that these unaffiliated are secular atheists.

Exactly. The unaffiliated category is large, and it is growing, and it is very important for social and political reasons. But that group is not monolithic, and it has within it a variety of different kinds people in it. The secular atheists are one group — an important group — but not everybody who is unaffiliated fits that category at all.