This weekend, Jeanne O’Hair, her friends and family will raise their voices in Easter hymns “as the spirit leads us,” she says, in her “house church” ― O’Hair’s living room in Brea, Calif.

In a metal outbuilding at a shuttered horse track near San Antonio, Jeff Bishop says he will celebrate at his “simple church” under a rough-hewed cedar cross, with “folks who speak ‘cowboy’ like I do.”

In Washington, DC, at the Saturday night Easter Vigil, “we’ll keep it casual and focused on Christ,” says William D’Antonio, a member of a network of Catholic-style house churches called “Intentional Eucharistic communities.”

No matter what you call them, house churches, or “simple” or “organic” churches, have long thrived in Third World countries where clergy and funds for church buildings are scarce. Now, however, they are attracting a small but loyal following across the U.S.

It’s not that Americans can’t find a conventional church congregation. Rather, millions of believers are leaving the pews for small, regular weekly gatherings where they pray, worship, study Scripture and support each other’s spiritual lives.

These groups operate without a building, a budget, an outside authority or, often, even a pastor. Many are lay-led groups where they like to say they “do church,” rather than “go to church.”

Participants are not “Christmas & Easter Christians” ― folks who pour into the buildings on peak holy days and fade away a week later. Instead, “they’re intensely active believers who want to take charge themselves and find something that feels more authentic,” said Christian research expert George Barna, author of a new book, Maximum Faith.

“If you look at the Bible, the church we have today is nowhere to be found. The original form of church was the house church. Older people want to find a more personal experience of God and young people don’t want the congregational structure or process. People don’t want to just read the responsive reading when they are told to,” Barna said.

A January 2011 survey by Barna Research (the firm that Barna founded and later sold) found that 5 percent of Americans ― about 11.5 million American adults ― say they attend a “house church or simple church, which is not associated in any way with a local, congregational type of church,” at least weekly or monthly.

That’s up from 4 percent (about 8.8 million adults) in 2006. Although the increase is slight, it’s clearly “more than a passing fancy. It has staying power,” current Barna Research President David Kinnaman says.

Before moving to California, O’Hair was on the staff of an Oregon megachurch that pulled out all the stops with Easter pageantry ― and later disbanded.

“We just weren’t seeing any fruit, any new members, for all that huge expense of time and effort. I love Jesus and I love the church, but I think the way we do institutional church in America will be extinct before long. It will just crumble,” O'Hair said.

Now, she says she’s happier celebrating her Christian faith with Sunday morning house church meetings and pot-luck breakfast with her spiritual family.

“We believe this is what Paul meant by the priesthood of believers, something that’s increasingly missing in the modern, hierarchical church,” said O'Hair, who works in accounting at a private Christian school.

Bishop, a retired fireman and acting director of the American Fellowship of Cowboy Churches, is not seminary trained or ordained, but has a license to conduct weddings.

“We’re not affiliated with any denomination, but we are affiliated ― we’re affiliated with Christ,” he says, using a favorite expression.

Bishop had taken the traditional church route, but said “I don’t miss a thing about it. This is church for people like me ― rural folk who speak my language.”

Ken Eastburn, an ordained Southern Baptist minister, checked out of traditional church a decade ago and jumped into a church without walls. Now he works with The Well, a network of eight groups like O’Hair's.

“The whole point is not to be passive about your faith,” Eastburn said. “Groups might meet on Sundays or on a weeknight but the constants are that there’s always a meal together, a time of sharing, a time of prayer and Bible reading, and listening to each other and God, not a pastor.”

Traditional churches have taken note of the growing desire for more simple ways to worship.

“Every large church I know is looking for ways to get small, to provide intimacy that may be missing,” says Kevin DeYoung,  pastor at the 500-member University Reformed Church in East Lansing, MI, and co-author of  Why We Love the Church: In Praise of Institutions and Organized Religion.

“Christians can meet anywhere from a cathedral to a storefront to a basement. There’s no one perfect model,” DeYoung said.

One drawback, he said, is that alternative congregations may drift away from church doctrine: “One of the main jobs of the church is to be the pillar of the truth, and its leaders are there to shepherd and guard it. It can be dicey in these small groups.”

Catholics like D'Antonio remain tethered to the historic church through the volunteer priests who serve the Eucharistic communities, even if many don't ask the local bishop for permission.

“People are weary of all the constraints,” says D’Antonio, a sociologist at Catholic University and co-author of a study, The Catholic Experience of Small Christian Communities.

“We may have about 45 people at Easter vigil, but when we light the Easter candle and march into worship, we’ll make as much noise singing as they will at any big parish.”

Cathy Lynn Grossman writes for “USA Today.”