When comedian Stephen Colbert brought his act to Capitol Hill last month and stole the spotlight with his satirical shtick, no one was more surprised than lawmakers.

"You run your show," House Judiciary Committee Chairman John Conyers scolded him, "we run the committee."

When Colbert finally let his well-coiffed hair down and got serious about the "really, really hard work" done by migrant farmworkers, even more people were surprised when the funnyman gave a glimpse of his private faith.

"And, you know, whatsoever you do for the least of my brothers, and these seem like the least of our brothers right now," Colbert said, quoting Jesus. "Migrant workers suffer and have no rights."

It was a different kind of religious message than Colbert typically delivers on Comedy Central's "The Colbert Report," where he often pokes fun at religion - even his own Catholic Church - in pursuit of a laugh. Yet it was the kind of serious faith that some of his fellow Catholics say makes him a serious, covert and potent evangelist for their faith.

"Anytime you talk about Jesus or Christianity respectfully the way he does, it is evangelization," said the Rev. Jim Martin, associate editor of the Jesuit magazine America, who has appeared on Colbert's show four times. "He is preaching the gospel, but I think he is doing it in a very postmodern way."

It's a contrast to Glenn Beck, the kind of right-wing media icon Colbert loves to skewer. While Beck's recent Restoring Honor rally in Washington was headed by a conservative broadcaster who embraces theological patriotism, Colbert's March to Keep Fear Alive on Oct. 30 will be helmed by a man of more private faith who leaves his God-and-country religion on the set.

Colbert has said that he attends church, observes Lent and teaches Sunday school. "I love my church, and I'm a Catholic who was raised by intellectuals, who were very devout," he told Time Out magazine. "I was raised to believe that you could question the church and still be a Catholic."

His on-air persona, meanwhile, is a bloviating holier-than-thou conservative whose orthodox Catholicism is part of what makes him funny. On air, Colbert has chided the pope as an "ecu-menace" for his outreach to other faiths, referred to non-Catholics as "heathens and the excommunicated" and calls those who believe in evolution "monkey men."

Diane Houdek has tracked Colbert's on-air references to Catholicism on her blog, Catholic Colbert. When he recites the Nicene Creed or Bible verses from memory, as he did in 2006, it shows how foundational his faith is, she said.

"He is moving in an extremely secular world - it is hard to get a lot more secular than Comedy Central," Houdek said. "Yet I feel he is able to witness to his faith in a very subtle way, a very quiet way to an audience that has maybe never encountered this before." It's particularly powerful to Catholics, Houdek said, when the lines blur between Colbert's personal faith and that of his on-air alter ego. She pointed to a 2007 segment in which his character reveled in Pope Benedict XVI's statement that non-Catholic faiths were "defective."

"Catholicism is clearly superior," Colbert crowed beside a picture of the pope. "Don't believe me? Name one Protestant denomination that can afford a $660 million sexual abuse settlement." It wasn't just funny, Houdek said, but "powerful."