Church volunteers greet visitors entering the lobby. The worship band begins its set and a pastor offers to pray privately with anyone during the service.

When the sermon is done, it's time for communion, and the pastor guides attendees through the ritual. Later, worshippers exchange Facebook and e-mail addresses so they can stay in touch.

There is nothing remarkable about this encounter, which is replicated countless times each weekend at churches around the world. It's all happening online.

The World Wide Web has become the hottest place to build a church. A growing number of congregations are creating Internet offshoots that go far beyond streaming weekly services.

The sites are fully interactive, with a dedicated Internet pastor, live chat in an online "lobby," Bible study, one-on-one prayer through IM and communion. (Viewers use their own bread and wine or water from home.) On one site, viewers can click on a tab during worship to accept Christ as their savior. Flamingo Road Church, based in Cooper City, Fla., twice conducted long-distance baptisms through the Internet.

"The goal is to not let people at home feel like they're watching what's happening, but they're part of it. They're participating," said Brian Vasil, Flamingo Road's Internet pastor.

The move online is forcing Christians to re-examine their idea of church. It's a complex discussion involving theology, tradition and cultural expectations of how Christians should worship and relate. Even developers of Internet church sites disagree over how far they should go. Many, for example, will only conduct baptisms in person.

The staunchest critics say that true Christian community ultimately requires in-person interaction. They deride the sites as religious fast food or Christianity lite.

But advocates consider the Internet just another neighborhood where real relationships can be built. Rob Wegner, a pastor at Granger Community Church of Indiana, which will soon launch its Internet campus, calls the Web the church's "front porch." Pastors who back the sites say they feel a religious duty to harness this new way for reaching the spiritually lost.

"We live in a day and age and a culture where people go to school online, bank online, date online and do other things online," said Kurt Ervin, who oversees the Internet campus for Central Christian Church, based in Henderson, Nev. "Why not create a platform for them to go to church online?" Central Christian started a new church service this fall on Facebook.

The sites share the same basic approach: rock-style worship music and a sermon recorded at the in-person weekend service that is quickly mixed with live or recorded greetings expressly for online viewers. Volunteers on live chat emphasize that day's Bible teaching and block inappropriate posts. (During one recent service, a man who said he was logged on from India wrote that he was looking for a Christian wife.)

Still, each has individual features.

At Seacoast Church, based in Mount Pleasant, S.C., online viewers can repent by posting a private record of their sins on a cross. Thumbnails of viewers' Facebook profiles appear during worship on Central Christian's Facebook Church so people can click on each others' pages to quickly connect. On the Granger site, visitors will be able to choose "seats" in an auditorium, then click on surrounding seats to exchange Facebook and Twitter addresses.

In this environment, evangelizing is nearly effortless. Regular viewers and volunteers post messages to their entire online network inviting them to the Web service in progress.

"Fifty years ago you could expect everyone to come to you," said Tim Stevens, Granger's executive pastor. "Now, we have to meet people where they are."

The phenomenon is so new that no one has an exact count of interactive online campuses. The Leadership Network, which studies and supports innovative churches, has found at least 40. Churches with the sites say they regularly receive calls from other pastors starting their own.

An Oklahoma megachurch named LifeChurch.tv in a nod to its use of technology is considered the pioneer of the form. The congregation had already expanded to physical sites in several cities when in 2006, pastors launched what they now call Church Online.

LifeChurch.tv now broadcasts more than 25 online services each week and plans more. The services collectively draw up to 60,000 unique views weekly, although the number of new computers that log on for several minutes is about 5,000, LifeChurch leaders say. Broadcasts are listed in Greenwich Mean Time, drawing viewers from more than 140 countries.

LifeChurch.tv has even found a way to attract people surfing for experiences that are far from pious. The congregation buys Google ad words so that a person searching for "sex" or "naked ladies" sees an ad inviting them to a live worship service instead.

Bobby Gruenewald, a pastor who oversees the online efforts at LifeChurch.tv, said the goal is to move people into some in-person Christian experience, in church, a small Bible group or even a group that watches online services together. He noted that many people watch online and attend a local church.

But he said some people are so transient that they have little opportunity to join a brick-and-mortar congregation. In countries where Christians are persecuted, a Web church is often the only way they can be reached, he said.

Amanda Sims, 38, of Starkville, Miss., was on Twitter during Christmas Eve last year when a friend posted that he was watching a LifeChurch.tv service.

She logged on and kept coming back, soon offering to volunteer online. She now works for LifeChurch as an online volunteer coordinator, managing a team of people from across the world who help with online worship.

One new friend whom she and her husband met online is a South Carolina-based truck driver who started watching LifeChurch.tv because he's so often on the road. When he drives through Mississippi, he stops in for dinner. He now volunteers for the site.

"It started out as augmenting my spiritual life, and it gave me a way to be in fellowship with believers I never would have met otherwise," said Sims, who still belongs to a local church. "They're like my family."