INDIANAPOLIS >> Imagine 475 college students — all members of fraternities and sororities around the country — flooding a hotel for a weekend. Imagine, come Sunday, that not one noise complaint has been lodged, no chairs are broken, no beer stains on the carpets and the hotel housekeeper says, “What a nice bunch of kids.”

Improbable, but that is exactly what happened recently when an evangelical Christian campus group, Greek InterVarsity, held a regional conference here to expand Bible studies and Christian recruiting in fraternities and sororities at mainstream universities.

Why would students who may not drink or believe in sex before marriage, and who read the Bible for recreation, want to join groups often known for hard partying, alcohol and hazing violations, and casual sex? Many said they enjoyed the companionship a house could provide and liked having friends of different or less ardent faiths. But many also said they relished the opportunity to spread the Gospel.

“Our goal is to help students lead a Christian life inside the Greek system, as contradictory as that may sound,” said Eric Holmer, the communications director for Greek InterVarsity.

The group is fighting a long-term decline in the share of students who say they are religious, as well as a tendency for church attendance to drop off during college. But it still sees fertile ground: In a 2007 national survey, 20 percent of college juniors identified themselves as evangelical Christians, according to Alexander W. Astin, professor emeritus at the University of California, Los Angeles.

The organization, a branch of a nondenominational campus ministry, has a foothold at 60 universities around the country, with 50 full-time staff members organizing on campuses. It counts about 2,800 active members from 367 Greek houses.

The conference here last month drew students from Purdue, Wisconsin and Michigan, among other institutions, and dozens of well-known campus houses like Alpha Tau Omega and Kappa Alpha Theta.

The students heard sermons from a pastor who easily segued from “U2 — I love that group” to “I love Jesus” and explored their feelings in small-group discussions on challenges to faith and how to start a Bible group in a fraternity or sorority house.

The leaders urged members to stay in the thick of Greek social life, rubbing shoulders with the sinners.

Jesus turned water into wine “to get the party going,” said a young woman who traveled here from Willamette University in Oregon, adding that parties were an opportunity to show that Christianity could be fun. After intense discussions, punctuated by Christian rock singalongs and an emotional evening session in which dozens stood up to signal that their faith was reborn, the members had a dance.

Kurt Skaggs, a junior at Indiana University, sees himself as something of a missionary. “Some people go to Africa or South America,” he said, explaining his decision to join Sigma Phi Epsilon. “I can go to my frat house, where my single goal is to glorify God and share the Gospel.”

Ten of the house’s 110 members have joined Skaggs’ Bible group. He said that while a few of his fraternity brothers “don’t appreciate” his views, most had a respectful, live-and-let-live attitude; he has even been elected house president. He said that he tried not to be preachy, but that he was not shy about confronting other professed Christians if they started drinking too much or engaging in casual sex.

With other students, Skaggs hopes simply to start the Christian conversation. “People do open up to you when they’re drunk,” he said. “They ask, ‘Why are you so excited all the time?”’

Christians who join fraternities or sororities can feel like outcasts in traditional Christian fellowships, said Kaitlyn Boyce, a junior at the University of Cincinnati, explaining why she was attracted to Greek InterVarsity. “People have these stereotypes and make assumptions about you.”

Boyce had not yet taken the scary step of standing up before her sisters in Delta Delta Deltato declare herself and call for a Bible study group. “It will be nerve-wracking,” she said. “These people mean a lot to you, and you don’t want them to think you won’t be fun anymore.”

At parties, she said, she tries “to take care of friends as much as I can, trying to minimize the damage” by, for example, telling a sister she has drunk enough.