"We just cover an enormous amount of ground that you couldn't cover if we didn't do it through song," Stone said of doing "The Book of Mormon."
Despite both men now having children in their lives, fatherhood hasn't seemed to slow down to soften the kings of vulgar cartoon comedy.
"I think there are people who are 30 who shouldn't watch 'South Park'," Stone said, laughing. "I have some friends who shouldn't be watching it. I always thought 'South Park' for about [age] 12...that seems about right."
Parker said that while he lets his 10-year-old stepson watch some episodes of "South Park" with him at home, there were times that he felt compelled to cover the young boy's ears during "The Book of Mormon."
"There's some hard-core stuff in the show, but it's not worse than a lot of 'South Park' episodes," he said. "We're able to pretty much say when people ask, 'oh can I take my kids to see this,' we're like, 'do you let your kids watch any episode of 'South Park'? If they say, yeah, we say, yeah, bring them."
The statement to ABC News from the Church of Jesus Christ of Latter-Day Saints said: "The production may attempt to entertain audiences for an evening but The Book of Mormon is a volume of scripture that will change people's lives forever by bringing them closer to Christ."
Parker jokingly boasted that he would give free tickets to members of the Mormon faith, including potential presidential candidates such as former Massachusetts Gov. Mitt Romney.
"We don't want to go out and make a Broadway show that's cynical," Parker said. "The thing I love about musicals is sort of how happy and optimistic a lot of them are...that's how a lot of them made me feel."