Then there is the Porn Mobile.

As a couple approached the car at the mall, demanding an explanation, Mr. Gross took the lead. He had studs in both ears, and surfer bangs with streaked highlights.

"We're pastors," he said. "We're trying to get people to talk about the issue of pornography."

"Awesome," said the woman, Cindy Mosher, 40, who said she had just come from church. "My previous husband was involved in porn, and that was one factor that destroyed our marriage."

"I'm in marketing, and you have to go for extremes," Ms. Mosher added. "Christian churches are quite traditional. To bring people in, maybe we have to go to extremes."

Internet pornography is one of the vexing issues for churches today, especially those that take strict moral lines on sexuality. Some consider viewing pornography a form of adultery; others decry erotic images as addictive and destructive to marriage.

Pastors, like school officials, often face severe punishment if they are found to have looked at Internet pornography. In 2000 Christianity Today magazine surveyed its readers (anonymously) and found that more than a third of the pastors who responded said they viewed pornographic Web sites, a number only slightly lower than their parishioners.

Even this figure is low, said Archibald D. Hart, a senior professor of psychology at Fuller Theological Seminary in Pasadena, Calif. "I do conferences for 3,000 pastors a year, and this is a biggie wherever I go," Mr. Hart said.

In response, churches and lay Christians have created a circuit of "sexual addiction" seminars, 12-step programs and even residential treatment centers, modeled on drug or alcohol detox centers, where people can stay for months at a time. Most address pornography as psychologically damaging rather than as a sin, Mr. Hart said.

Mr. Hart, who surveyed pastors for his 1995 book, "The Sexual Man," said that most pastors and church members used Internet pornography at one time or another.

"In some of the more conservative denominations it is silent, it's a secret, no one talks about it," he said. "And those pastors are frankly in denial about the impact of pornography."

For Mr. Foster and Mr. Gross, who were both involved with conservative churches, the issue called for a generational break: not condemning pornography from on high, but forming relationships with both the producers and its consumers, including pastors.

Neither draws a salary from XXXChurch.com. Mr. Foster is also the communications pastor at Crossroads Christian Church, a nondenominational church in Corona, Calif. Mr. Gross speaks to Christian youth groups around the country as a founding partner in Fireproof Ministries, a nondenominational youth ministry.

Their unorthodox calling is the subject of "Missionary Positions," a documentary film made by Bill Day, a secular filmmaker. The documentary is rated R and includes profanity and suggestions of nudity.

On an autumn afternoon in Los Angeles, Mr. Gross and Mr. Foster attended a screening of the film, along with an audience that included James DiGiorgio, the pornographer who directed their public service announcement, and Ryan Dobson, the son of James Dobson, founder of the conservative Christian group Focus on the Family.

"The church has gotten prissy in not going to the porn conventions," said the younger Mr. Dobson, 34, who runs a ministry for surfers and skateboarders. "God bless Craig and Mike for doing it. I don't want to do it."

"I loved the movie today," he added. "I wouldn't play it in my church. But if you beeped out the swear words and covered up some of the nudity, I'd totally play it in my church." He said that the senior pastor at his church uses X3watch software and talks about it from the pulpit.

"He talks about his struggle with pornography," Mr. Dobson said. "He says, `I have X3watch on my computer, and my wife is one of my accountability partners. Why? Because I struggle. And I know people out there struggle as well.' I flock to a guy like that, because he's honest about it. We struggle together."

Mr. DiGiorgio, whose films include "Bodyshop Girls" and "Punished in Plaid," and who works under the name Jimmy D, took a different view of his unlikely collaborators. He appreciated that they did not preach at him, as other ministers had, he said. But mainly he liked their nose for publicity.

"These guys are like guerrilla marketers, they recognized right away that a controversial relationship would spark interest in the media," he said. "They saw it as I saw it."

In the movie Mr. DiGiorgio is seen filming a sexual act that he says he finds repugnant. But of his collaboration with Mr. Gross and Mr. Foster, he said: "I didn't do it for any kind of Christian value. I respect their faith, and so far they've respected my lack of it. I'm the first guy to admit that I'm sometimes conflicted about what I do. I've expressed that to them. But have they tried to minister to me? No, not really."

To Mr. Foster and Mr. Gross, their relationship with Mr. DiGiorgio, like their attendance at pornography events, gives them leverage to address the people scared away by church. "If Jesus were around today," Mr. Gross said, "he would be at porn shows. But most Christians would rather preach to Jimmy D, and if he doesn't accept Christ, move on to the next person. And you might reach more people, but Jesus worked with 12 people."

In the mall parking lot, Lana Olsen, 54, said she did not appreciate the shock tactics. "To me that is crossing the line," she said of the car. "I decided this was a porn person trying to make fun of the church. My son, an atheist, would think that's the enemy's greatest tool."

But Andy Allman, 19, who worked in the mall Starbucks, liked the car. "You guys are anti-porn, right?" he asked. When Mr. Gross explained that they were pastors, Mr. Allman, was interested. "Really?" he said. "Because I've been looking for a church. Can you recommend one?"