For Catholics raised during the head-spinning days after Vatican II, few things inspire flashbacks to the era of flowers and folk Masses quicker than the bouncy hymn "The King of Glory." But what was a goofy nerd doing on Comedy Central, belting out this folk song while doing a bizarre blend of Broadway shtick and liturgical dance?

"The King of glory comes, the nation rejoices! Open the gates before him, lift up your voices," sang Stephen Colbert a decade ago, in a video that is now a YouTube classic. "Who is the King of glory; how shall we call him? He is Emmanuel, the promised of ages."

Inquiring minds wanted to know: Was this painfully ironic comedian mocking trendy Catholics or saluting them? Was he outing himself as a Christian? Was he praising Jesus or risking a lightning bolt?

Legions of 40-something Catholics have strong memories of the first time they saw this clip, said Diane Houdek, managing editor of AmericaCatholics.org. Something in Colbert's performance told them that this was not a random gag.

"Stephen walks this thin line," said Houdek, who runs "The Word: A Colbert Blog for Catholic It-Getters" in her spare time. "He isn't afraid to be critical when it comes to matters of faith, but when he does it's always clear that his critique is from the inside. ... He'll push things pretty far. He'll dance right up to that line, but he will not cross it. He will not compromise what he believes as a Catholic."

Colbert, of course, became the star of The Colbert Report, the fake news show in which he plays a right-wing egotist (think Bill O'Reilly of Fox News) named "Stephen Colbert." Religion plays a major role in the show and there are moments when he speaks sincerely in his own voice.

That's what happened last week when his alter ego came to Washington, D.C., at the invitation of Rep. Zoe Lofgren (D-Calif.), chair of the House Judiciary Subcommittee on Immigration, Refugees and Border Security. His testimony mixed satire ("I don't want a tomato picked by a Mexican. I want it picked by an American, sliced by a Guatemalan and served by a Venezuelan in a spa where a Chilean gives me a Brazilian") with serious information about the plight of farm workers.

Colbert lowered his mask when asked why this issue mattered to him, slipping in a reference to a Gospel of Matthew parable in which eternal judgment awaits those who deny compassion to the poor and defenseless.

Some of America's least powerful people, he said, are "migrant workers who come in and do our work, but don't have any rights as a result. And yet, we still ask them to come here, and at the same time, ask them to leave. ... You know, 'Whatsoever you did for the least of my brothers,' and these seemed like the least of my brothers, right now."

It helps to know that Colbert was raised as the youngest of 11 children in a devout Irish-Catholic family in Charleston, S.C. Then his physician father and two brothers died in a plane crash and their joyful home plunged into grief. Colbert soon lost his faith.

Years later, a sidewalk volunteer in Chicago handed the young actor a Gideon Bible and something clicked. Today, he lives a private life with his wife and three children, but he never hides the fact that he teaches children's Sunday school.

As he told Rolling Stone last year: "From a doctrinal point of view or a dogmatic point of view or a strictly Catholic adherent point of view, I'm the first to say that I talk a good game, but I don't know how good I am about it in practice. I saw how my mother's faith was very valuable to her and valuable to my brothers and sisters, and I'm moved by the words of Christ, and I'll leave it at that."

But there is more to Colbert's faith, and his theology, than that, said Houdek. For starters, a Jesuit serves as the show's chaplain.

"There is evidence of his faith all through his work, if you know what to look for," she said. "This is what makes him so unique, in the extremely secular world in which he is working -- Comedy Central. Yet he keeps doing what he does night after night, because he never comes off as preachy."