If you're a fan of the series "South Park," and especially of the transcendent feature film it spawned, you had certain expectations of "The Book of Mormon." You expected the Broadway musical, created by South Park auteurs Trey Parker and Matt Stone and Avenue Q mastermind Robert Lopez, to be profane. You expected Mormonism in particular and religion in general to get something of a lyrical rogering.

But you probably didn't expect the work to be sort of sweet and accepting. And perhaps no one expected the show would be quite so excellent measured simply as a straight up, all singing, all dancing piece of musical theater.

"The Book of Mormon" was born in 2004 when "South Park's" Trey Parker and Matt Stone met "Avenue Q" mastermind Robert Lopez and the three discovered a weird mutual aspiration to create a work based on the father of Mormonism, Joseph Smith. That idea evolved over six years into a musical, directed by Parker and choreographer Casey Nicholaw, to tell the story of two mismatched Church of Jesus Christ of Latter Day Saints missionaries who are sent to Uganda to grow the flock.

Given the project's architects and the subject matter, yes, it's a tad, um, irreverent (one of the early numbers is "Hasa Diga Eebowai," which, translated, is a deeply unpious imperative, directed at God). But the intention wasn't just to crap all over gormless believers in a series of preposterous founding myths. As Mr. Parker told the New York Times, "We wanted to make this not just cynical and Mormon bashing, but hopeful and happy, because to me that's what musicals are about."

Whether you think Parker et al should have skewered Mormonism more thoroughly, or whether the whole premise horrifies your religious sensibilities, if you see the show, it's difficult to escape the conclusion that Messrs. Parker and Stone have conquered yet another medium. (In the meantime, they continue to produce "South Park" at an alarming rate, a deal with Comedy Central through 2013 reportedly tops their last $75 million package and they crank out an episode a week.)

Critics can't decide if "Mormon" is a return to classic Broadway form -- both the New York the L.A. Times reviews referred to the show as old-fashioned -- or something completely new. The Hollywood Reporter called it "one of the freshest original musicals in recent memory." But they've generally agreed that it's just massively entertaining. And they're not alone. Tickets sales are brisk and the musical led the pack in Tony nominations with 14 nods.