Matt Stone and Trey Parker may grab the headlines, but Les Freres Corbusier got there first. The increasingly important and ever-entertaining downtown performing troupe introduced their delightful musical, A Very Merry Unauthorized Children's Scientology Pageant, a couple of years before Stone and Parker's infamous South Park episode "Trapped in the Closet" publicized Scientology doctrine on a previously unimagined scale.

But the episode pulled a few punches; Pageant can't be bothered, though its uppercuts come by way of toothsome smiles and adorable young actors. As brutal as it is brutally funny, Pageant was a huge Off-Off-Broadway hit in 2003, and has now returned to New York to grace the season with joyful sights and songs - and some of the most withering criticism the Church of Scientology has ever received. If you already know all about what Scientology is and how it works, a trip to see this first-class remounting at the New York Theatre Workshop might just mean a rampantly entertaining evening; if you don't, it's an eye opener as horrifying as it is hilarious.

Written by Kyle Jarrow from a concept by Alex Timbers (who also directs), Pageant spins the life and work of Scientology founder L. Ron Hubbard into a crayon-colored holiday playlet reminiscent of those you might see in a low-budget community theater or a dank church basement. The scenic design (by David Evans Morris), costumes (Jennifer Rogien), and lights (Juliet Chia) all look cobbled together from used parts and half-formed ideas (why exactly is a young girl running around in an angel costume?), as if their very presentation is all that's required for edification: The effort alone is half the fun for everyone.

But as performed by 10 children rather than by adults, the performance takes on darker overtones that make these youngsters' unseen parents crucial supporting characters. As the pint-sized cast relates Hubbard's history of science-fiction writing and psychological correction by way of Dianetics, the philosophy of the competing analytical and reactive minds (as represented by two children sharing a ridiculously right brain costume), and Scientology's most secret doctrine of a galactic warlord named Xenu who's responsible for all our problems and fears, you can't help but wonder exactly what these kids are being taught.

In the bittersweet climax, set (as so many Scientology confrontations are) in a courtroom, the kids even attempt to answer criticism of Scientology with the unshakable belief of people learning to question nothing, for a captive audience of similar true believers. (Tom Cruise, complete with Katie and Suri hand puppets, makes a cameo appearance.) Directed so lightly by Timbers, and enacted so honestly and enthusiastically by the cast - if one of them is aware of the joke, he or she never lets on - the show entertains on so many levels, you never notice its razor-edged propaganda until Jarrow finally breaks down after 60 minutes and stabs you in the face with it.

He needn't have bothered. The rest of the show speaks so hauntingly about the seductive power of corruption that to lay out all his cards is a subversion of something already grippingly subversive on its own. The show's blithe, twinkling melodies, the kids' winning attitudes toward even the most ridiculous lines and scenes, and their dutiful presentation of Someone Else's staging and steps is wonderful on its own terms, and it's easy to see how it could quickly captivate one unaware of its sardonic, satirical bent.

The real show, though, Jarrow reminds is, is the one happening offstage. Except for some momentary interruptions, such as when the young actor playing Hubbard (the fine William Wiggins) tries to get a confused costar back on track and pushes too far too quickly, we don't see much of it here. That's just as well - it's a more appropriate tale for Halloween than for Christmas. But A Very Merry Unauthorized Children's Scientology Pageant is welcome any time of the year.

A Very Merry Unauthorized Children's Scientology Pageant
Through January 7
New York Theatre Workshop, 79 East 4th Street between 2nd Avenue and Bowery
Tickets online and current Performance Schedule: Telecharge