Rachel Gimber hadn't been a churchgoer in years, but the small congregation she discovered nine months ago in West Chester instantly felt like home.

The Meeting House church had no imposing stone façade, no vaulted ceiling or stained glass windows, no sign of denomination. It was simply what its name conveyed: a group of believers meeting in a house.

"Sometimes when I walked into a church and didn't know anybody or feel a connection, I almost felt judged," said Gimber, 27, a financial portfolio manager from Collegeville, who grew up Catholic. "But in Meeting House, it's a family setting, and they met me where I was."

So two weeks ago, she stepped into an inflatable swimming pool in its backyard, sat down in two feet of water, and was baptized during a Friday evening cookout.

The Meeting House is one of dozens of home-based churches in the Philadelphia area that have been opening their screen doors to Christians who want to shed the trappings, if not also some of the underpinnings, of institutional religion. They come to re-imagine worship, to practice their faith unencumbered by traditional liturgies — not to mention the burdens of building maintenance, budgets, and programming.

Usually unaffiliated, house churches — also called "organic" or "simple" churches — might be as minimal as three people sitting at a kitchen table or as large as 50 overflowing a living room. Hierarchies tend to be frowned upon, even though ordained ministers, like Don Graves of East Oak Lane, can be found among the faithful. True to the house church spirit, he eschews the title "reverend." A "smaller, more intimate and participatory" church, he said, offers a different way of carrying out the resurrected Jesus' Great Commission to his disciples to win souls.

House church services can be on Sunday mornings or on weekdays after work. Rituals are reshaped to fit the inclinations of the group or tossed aside altogether; in place of sermons are discussions. Music might be a ditty composed on the spot by a congregant.

"The most grassroots groups can really just make it up," said Nancy Ammerman, a professor of sociology of religion and an associate dean at Boston University. "They draw on patterns of study, preaching, liturgy that they already know, but won't be constrained by any particular denomination or authority that tells them that you can do this or you can't. That's one of the things people like. They have freedom to innovate."

Because most house churches operate under the radar, their numbers are difficult to estimate. At least 30 appear in online listings in Southeastern Pennsylvania and South Jersey. In a 2009 national study by religion researcher George Barna, as many as 6 percent of respondents said they were part of a "group of believers that meets regularly in a home or place other than a church building." At the time, Barna estimated their ranks countrywide at between six and 12 million, and predicted substantial growth.

Even mainline denominations are examining the model as they grapple with declining memberships. The Southeastern Pennsylvania Synod of the Evangelical Lutheran Church recently accepted two house churches as affiliates to explore new ways of worship that might broaden the base.

Internationally, in nations such as China, where atheism was once official, underground house churches have long sheltered millions of Christian believers. But the practice dates back much farther, to early Christianity. In the New Testament, missionaries Aquila and Priscilla, friends of the apostle Paul, opened their home in Ephesus to followers of the Corinthian church.

Members of Hunting Park House Church are so committed to reclaiming the simplicity of the early church that they have turned away from Facebook and other social media to reach potential converts, maintaining that Christians should do that in person. Congregants have even disagreed about distributing a flier. Some said "we are the flier," said the Rev. Andres Fajardo.

In West Chester, the Meeting House congregation, a community of about 50, is going full-bore at the home of  Fred Balliet, co-pastor with founder Robb Hollman. Monday is Bible study, Tuesday is youth group, Friday is a community dinner (when Gimber was baptized), Sunday is church.

"It's life together every day," Balliet said. "Some might not come to one, but to others. People mix and match."

At the South Jersey home of Roseann Metrinko in Winslow Township, the Saturday meeting of Seventh-day Adventists was originally a replica of the traditional church service, but evolved into a stripped-down Bible study and dinner.

"We thought, why are we going through the motion of doing all this when what we really wanted was a more relaxed, more interactive atmosphere?" said Metrinko, who had served as the women's ministry leader of the Seventh-day Adventists' New Jersey conference.

The congregation is part of the Simple Church at Home Network, a lay-led aggregation of about 250 house churches in 23 countries, most in the U.S. The congregations average 12 members. Founded nine years ago by Milton Adams, a Linden, Tenn., teacher who holds a doctorate of ministry, the network offers Adventists a place to worship where they "won't get corrected, reprimanded or set straight by someone who sees themselves as an authority figure," he said.

Ron Pizzo of West Norriton and Bill Posey of Warminster started churches in their homes after becoming disillusioned with their former non-denominational congregations. Both shopped for new churches but wound up holding services in their living rooms.

"We were looking for the perfect church. Of course, there isn't any," said Posey, who hosts a group of five to 10 at his home on Sunday evenings — although if that's inconvenient for most, just about any other evening will do.

Because they're small, house churches are more vulnerable to the destructive effects of change, whether the loss of members or conflict among them.

At her King of Prussia house church, Roseann Howell has watched families relocate, return to the traditional church or just leave. One house church she belonged to disbanded.

Indeed, the ties that bind can fray easily, Ammerman said. She puts the average life of a house church at about five years.

"If they don't have a denomination behind them, a building they're tied to or a history that they they feel an obligation to — these are all things that keep most religious communities together," she said. "Part of the appeal of house churches is that they don't have those things, but it also means it's harder to keep them going."

As outliers of the traditional church, house congregations often operate with little or no oversight. They can be magnets for perpetually dissatisfied people who flit from church to church, as well as ambitious leaders aching for power, no matter how small the platform, said David Anderson, creator of the House Church Network website, which has kept a listing of house churches for 20 years.

"Anything you can find wrong with the organized church," he said, "you can find it in house churches."

Simple Church at Home provides leadership training and requires house congregations to report weekly to counselors. Donations are deposited into individual church accounts and used only for local charitable causes, Adams said.

New affiliates of the local synod, the two Lutheran congregations grew out of the closing 10 years ago of St. James Evangelical Lutheran Church in Chalfont. Members began meeting in their homes to pray about their next move, and "we kept on meeting," said Bob Fisher, an assistant to Bishop Claire Burkat of the synod. The groups call themselves Kairos, a Greek word for "opportune moment." To Christians, it refers to the appointed time to fulfill God's purpose, Fisher said.

At a combined meeting in early August in Souderton, 15 members discussed the parable of the sower and took part in an "Agape meal," or love feast. Each broke a piece from a round loaf of bread, dipped it into a bowl of grape juice, ate it, and so it went around the living room circle — a ritual affirming the presence of God.

"Having been in a church that struggled and closed because of [expenses], the idea is to be sustainable," Fisher said. "We want to focus our energy and passion on being the church out in the world, rather than simply supporting the superstructure of a building."