When Clark Johnsen takes the stage as a member of the ensemble in "The Book of Mormon," he knows whereof he sings and dances: Mr. Johnsen, 34 years old, grew up within the Church of Jesus Christ of Latter-Day Saints, graduated from Brigham Young University and spent two years on a religious mission in Mexico.
Playing a Mormon onstage is one of the last things he ever planned to do. "If someone had said 'You're going to play a missionary on Broadway'—while I was shlepping 10 Books of Mormon around Mexico—I would have said 'Well, that's impossible. There's never going to be a musical about the Book of Mormon.' "
But in fact "The Book of Mormon"—with nine Tony Awards to its credit—turned out to be a hit. And though Mr. Johnsen has since broken away from the church, his upbringing made him a perfect fit for the show. A resident of Hell's Kitchen, this triple threat grew up singing and playing the piano and clarinet as part of a well-rounded childhood. "That was part of our family script," he said. "We play instruments. We are good at sports. We get good grades. We have lots of friends."
That was just the first stage in his artistic development. While at BYU as a pre-med student, he took dance classes to fulfill physical-education requirements. His dance teachers encouraged him, as did his academic advisers—on the thinking that a liberal-arts major would stand out, he recalls: "How many modern dance majors were there going to be applying for med school?"
In the end, Mr. Johnsen wanted to focus on his acting and graduated with a musical theater major. Then, during his mission in the Sinaloa state of Mexico, he learned the skill that every actor needs: how to handle rejection.
"Doors were slammed in my face all the time. You must develop a plucky attitude," he said, comparing missionary work with the casting process. "You just know: This isn't about me."
After graduating from college, he struggled with the idea of heading directly into medical school. "I thought, 'I'm just going to move to New York for two years and give it a shot,' " he said.
That was 10 years ago. In that time, he landed in "The Addams Family," "42nd Street" (in Russia) and "La Cage Aux Folles" (directed by Jerry Zaks and Jerry Mitchell). When he joined "The Book of Mormon," he was the only newcomer to the cast that had been workshopping the musical since 2007.
"Clark understood the tone of the piece and the sense of comedy. He nailed it right away," said casting director Carrie Gardner. "It's super friendly, always happy, but slightly heightened so you can laugh at it, though not too much. Clark has an open, bright, happy face. That's what draws people in."
Indeed, even in speaking about his life and path, Mr. Johnsen has an earnest, sunny bearing. "What forged the ultimate positivity of the Mormon character was the trek across the Plains. I don't believe in the religion at all, but it makes me emotional to think about those people trekking across," he said.
As a young person, however, he did have to face the church's position on homosexuality, which lead to periods of "constantly dissecting in my head every choice and thought." It was a process that had implications onstage. "My acting teachers in college would say 'All you are doing is thinking. You are not feeling anything. You need to evoke emotions in others. You're being so cerebral,' " he said, adding that such observations only made him more so. "I was like, 'What do you mean by cerebral?' "
Before he left for his mission in Mexico, he had already come out to his parents and church leaders. When some of his companions on the mission (who change every three months or so, unlike in the musical) asked about his sexuality, he was honest with them.
"They would say, 'I'm glad you're trying to beat this thing,' and they would always share something with me, too," he said. "It opened a door for an emotional bond to form."
While the musical version of a young Mormon's mission is played for laughs, Mr. Johnsen is more amused by the similarities than offended.
"The costume is exactly what I wore on my mission—only the name tags are bigger," he said. "And the way my hair is parted, that's how I used to wear it."
The Mormon reaction to the show, he says, is somewhat positive because it introduces the church's story. "Starting with Joseph Smith, there is this dream of fame, spreading throughout the world," he said.
Despite his independence from the church, Mr. Johnsen—who has four siblings who are still active in the church and two who aren't—considers his experience a net gain of life skills, including the ability to meet new people easily, ask questions and network professionally.
"I don't regret a second of it," he said.