Kurt Frederickson often makes the case that pastors need to change how they engage their shrinking congregations. And now he has even more research on his side.

When Fredrickson, an associate dean at Fuller Theological Seminary in Pasendena, Calif., speaks to an annual gathering of Evangelical Covenant Church pastors this week in central Michigan, he will be armed with the latest data describing people who don't affiliate with a church — a group that is growing faster than any other religious tradition.

A report released last week by the Pew Forum on Religion & Public Life showed that while America remains religious, with 79 percent of the population saying they belong to a faith, the number of those who say they don't belong has grown 4.3 percentage points in the past five years. The rise is particularly acute among young adults.

The possible causes of the trend vary from a general distrust in large institutions to an increasing number of people feeling comfortable with disclosing they are unaffiliated with a church, according to Pew researchers and other experts.

Opinions on how to reverse the trend also vary. Some say the rising number of unaffiliated people is a healthy weeding out of "anemic Protestantism," while others say the unaffiliated simply seek spiritual fulfillment in a variety of ways and are not as irreligious as studies suggest

But Fredrickson says the data clearly show that only those church leaders who can find a way to connect with the unaffiliated and with the surrounding communities at large will be able to keep their doors open in the future.

"We need to do church and religion differently to connect with people," says Fredrickson. "We need to change the whole tenor of the religious experience into something deeper and more meaningful" than just stitting in a pew one day a week.

'Nones' on the rise

Pew's latest analysis, titled "'Nones' on the Rise," was a deep dive into several surveys dating back to 2007 and included a poll of nearly 3,000 adults conducted June 28-July 9, 2012. ("Nones" is the nickname given by demographers to people who, when asked their religious affiliation, answer "none.")

The analysis found that, due in part to the increasing number of "nones," the percentage of Protestant adults in the U.S. has dropped to 48 percent, marking the first time in history that the United States does not have a Protestant majority. It also found that less religiously active Americans are becoming more comfortable saying they are unaffiliated. In 2007, 38 percent who seldom attended a religious service identified as unaffiliated. In 2012, that share grew to 49 percent.

The unaffiliated are predictably less religious than the public at large on conventional measures such as church attendance, prayer and the importance they place on religion, but they are not completely irreligious. More than two-thirds (68 percent) say they believe in God and 37 percent classify themselves as spiritual but not religious.

Researchers also found that the unaffiliated believe religious institutions benefit society by forging community bonds and caring for the poor. But few of them (10 percent) are seeking out a faith, and they overwhelmingly say organized religion is too involved in politics, focused on rules and concerned with money and power.

"What that tells me is these people aren't looking to religion for answers," Fredrickson said. "They don't trust the institution."

He believes the church can earn that trust by changing its paradigm from an "attractional" model that uses marketing, liberal doctrine or a contemporary worship style to fill up the pews to a model that focuses on helping the community at large live Christlike principles to make their community a better place.

"In Protestantism too often the measurement is bodies, budgets and buildings. It feels fake to people if we are just trying to get numbers," he said. "But if the goal is instead to make the world a better place in Jesus' name, then the responsibility of the church is to do good things."

Clearing the ranks

Not all clergy think the growing number of "nones" requires an overhaul in the church.

Russell Moore, a dean at the Southern Baptist Theological Seminary in Louisville, Ky., sees the shift as a necessary clearing of the ranks of uncommitted who "hid behind a Christian mask to appear as a good American."

"I think the collapse in the majority is a good thing in that what is collapsing is weak, anemic Protestantism," Moore said.

He envisions what will take its place is a thriving form of orthodox Christianity that distinguishes itself from popular culture. "Some churches are in their death throes because they are indistinguishable from cultures around them," he said.

"Sometimes animists, Buddhists and body-pierced Starbucks employees are more fertile ground for the gospel than the confirmed Episcopalian at the helm of the Rotary Club," Moore wrote in a farewell to the Protestant majority. "Accordingly, evangelicals will engage the culture much like the apostles did in the first century — not primarily to 'baptized' pagans on someone’s church roll, but as those who are hearing something new for the first time."

How the unaffiliated would respond to the new eras Fredrickson or Moore envision is uncertain. Pew researchers found that while there is considerable churn in and out of church affiliation by individuals, the percentage of a generation that is unaffiliated doesn't change as it gets older.

If generational trends dating back to the 1970s hold true, most of the under-30 generation who identify as unaffiliated will remain so into their senior years. Pew researchers said that more than 30 percent of the unaffiliated are 30 years old, making that generation the most disconnected with traditional religion than any before them.

But they will likely always remain a minority, predicts Joseph Baker, a sociologist at East Tennessee State University who has studied and written about the religiously unaffiliated.

"They are a bit demographically disadvantaged because people who are not religious tend not to have as many children as those who are more religious," he said.

Still, their disinterest in organized religion presents some unknowns about how they will raise their families and engage in their communities, he said.

"Religion has traditionally helped families socialize their children in morality. The question is what strategy these people will take in the moral socialization of their children," Baker said.

Turned off by labels

Elizabeth Drescher, a religion scholar at Santa Clara University who is researching the spiritual practices of the "nones," said they will likely turn to others like them in the social networks they have built digitally or in person.

"People are finding themselves in different ways by being networked to other people who have affinities in spiritual interests," she said.

Drescher said the labels of "none" or "unaffiliated'' can lead to inaccurate conclusions that someone who does not want to sign up isn't religious or doesn't participate. She compared the religiously unaffiliated to independent voters who are engaged politically and reliably vote Republican or Democrat but don't want to be identified with either party.

"I am still working on the data, but anecdotally I am finding people who go to church or may be involved in a community but they just don't like the terminology of 'affiliated,'" she said. "These people don’t want to be pledging units. They want to be who they are and valued in their uniqueness."

If the unaffiliated are spiritual peole who are simply turned off by labels, that should give hope to American faith leaders who worry that the United States could go the way of Western Europe, where Pew researchers say about one in five or fewer say religion is important in their lives compared to 58 percent in America.

But if clergy want to tap into the unaffiliated, they must join the social media revolution and converse as an equal and not as the authority on spiritual matters, Drescher explained.

"That’s not to say they don't want have conversations about the implications of their faith commitments," she said. "What they don't want to hear is any kind of messaging that's meant to direct their behavior. That top-down directive ... narrowing the conversation and narrowing choice is not going to be attractive."

Drescher predicted that some churches will die as organized religion readjusts to better communicate with engaged people within and without the faith.

"The challenge for church leaders is how do you move people from just consuming church (online or in the chapel) to having them be active in the world as a result of their engagement with other people with common spiritual interests?" Drescher said.

For Fredrickson, making that shift from just focusing attendance within the walls of the church to being relevant and meaningful to the surrounding community can stem the rise in the "nones."

"Maybe more people will end up at church out of that, but maybe that is not the most important value," he said. "Maybe the most important value is that we are working to make the world better."