If American religion is a spiritual shopping center, denominations that once dominated the market are in danger of being boarded up.

A major survey of 35,000 Americans released this week by the Pew Forum on Religion and Public Life confirms the long-held belief that denominational loyalty is fraying — and those with much at stake include both mainline Protestant and evangelical churches.

Yet to some observers, woven into the gloomy numbers is a road map for survival, if not success, if denominations get more nimble and creative while not compromising core beliefs.

Sociologists point to many factors in the erosion of denominational loyalty, including a transient population less anchored to one city or job and the rise of individualized faith, including people who borrow from many traditions.

"As with most things, for Americans religion is a consumer product," said the Rev. Eileen Lindner, a Presbyterian minister who edits the Yearbook of American and Canadian Churches.

"So it's not brand loyalty you can rely on. It's marketing, location and other things. Denominations have been slow to react to that."

The Pew survey found many Americans don't want to be associated with denominations, even when they belong to one. People who call themselves "just a Protestant" account for 5 percent of the adult U.S. population.

Even when given the chance to choose from specific denominations, many people said, "I'm just a Baptist," for instance — even though the Baptist family ranges from strongly conservative to smaller liberal traditions.

About 16 percent of Americans are unaffiliated with any religious tradition — an increase from earlier surveys — although many of those say faith is important to them. Nearly half of American adults have left behind the faith tradition of their upbringing.

"It would be wrong to view what's happening as a shift from one religious identity to a different religious identity," said Alan Wolfe, director of the Boisi Center for Religion and American Public Life at Boston College. "What we've been witnessing is a shift from a fixed identity to a fluid identity."

One key finding of the Pew survey: Nondenominational Protestants are growing in number and tend to be younger. About three-quarters of nondenominational Protestants fall under the evangelical tradition, said Greg Smith, a research associate with the Pew Forum. But in a conclusion that might surprise some, Pew researchers also identified 20 percent of nondenominational churchgoers as mainline Protestants.

(The numbers are from a Mainland perspective, since Alaska and Hawai'i were not included in the study. Also, proportionately, more respondents were from the South than from other regions.)

Smith said the mainline tag was applied to people who attended nondenominational churches but did not identify themselves as born-again or evangelical Christians, and to those who said they attended "liberal nondenominational" or "emergent" churches. Many emergent churches borrow the worship and liturgical styles of mainline Protestant churches but hew to a conservative evangelical theology.

The decline of mainline Protestant denominations and rise of evangelical churches in the 20th century is well documented, with many contributing factors: mainline Protestant churches are aging faster, recording lower birth rates, attracting fewer immigrants and embroiled in divisive battles over sexuality and the Bible.

The Rev. Lovett H. Weems, Jr., director of the Lewis Center for Church Leadership at Wesley Theological Seminary in Washington, a United Methodist Church seminary, said growing churches have both a clear sense of identity and meet people's needs in a changing culture: "They're not just setting up shop and saying, 'This is who we are, these are our beliefs and we will be here if anyone wants it.' "

As the nation is on the cusp of becoming minority Protestant, it isn't just the old mainline that should be concerned, said D. Michael Lindsay, a Rice University sociologist and author of "Faith in the Halls of Power: How Evangelicals Joined the American Elite."

Lindsay said his survey of people in positions of power at major evangelical organizations found 60 percent had low denominational loyalties.

The nation's largest Protestant church body, the 16.3 million-member Southern Baptist Convention, is aware of the sentiment. The proportion of young adult lay people and pastors who serve as "messengers," or delegates, to the convention's annual meeting has been dropping since the 1980s and declined sharply since 2004.

After growing steadily from 1950 to the mid-1990s, the conservative-dominated Southern Baptists have experienced relatively flat growth, causing alarm.

In another sign of the times, more than half of new Southern Baptist churches don't use the word "Baptist" in their name, recent church research found. One older example is blockbuster author Rick Warren's Saddleback Church in Southern California.

The Rev. Frank Page, president of the Southern Baptist Convention, said he sees opportunity in reaching out to spiritual wanderers in the nation's evolving religious marketplace but also danger in a culture that does not value absolute truth.

"It points to a shallowness in our society, where people don't care about what really matters," said Page, pastor of a large South Carolina church. "It's a consumer society. People look at what looks good on the surface — the bells and whistles. People are apt to ignore substantial issues they deem unimportant."

Advertiser Religion & Ethics Writer Mary Kaye Ritz contributed local information for this report.