The renegade comic spirit and danger of John Dower’s brilliant documentary My Scientology Movie can be summed up by one scene (watch clip here), during which BBC broadcaster Louis Theroux takes a trip to the notorious church’s Gold Base in the California desert. He’s met on the road by an irate Scientologist named Catherine Fraser, who goes berserk when Theroux tries to show her his legal permit to access an adjacent road. Their interaction seems so much like a Monty Python skit that you can practically hear John Cleese and Eric Idle (him in drag) speaking the lines. Fraser forbids Theroux from filming her, even though she arrives armed with her own cameraman. The two lock horns verbally, each demanding that the other cease recording. The effect is hilarious while also deeply unnerving—and buoyed by Theroux’s amazing calm in the face of absurdity.

Earlier in that same scene, he’s gazing upon the Gold Base’s razor-wired fence as the sun is quickly fading. Gigantic prison-style floodlights illuminate all around him and he quips, “That’s quite helpful actually.” Floodlights aren’t so scary when you’re a documentarian. In past works Theroux has embedded with Neo Nazis and the Westboro Baptist Church, among many other ghoulish sidebars of society. His approach is shaggy and disarming, and quite deceptively so. For his proposed study of Scientology, Theroux was barred from getting inside the church or interviewing any of its hierarchical members. And so instead, he attempts to understand the inner workings by recreating the religion’s practices and some of the most controversial alleged events from its more recent history.

That’s where Andrew Perez, a gifted, intense Los Angeles stage actor, steps into the film and delivers its most dazzling moments. He portrays the mysterious Scientology leader (and heir to L. Ron Hubbard) David Miscavige, who hasn’t given an interview since 1991. In a shorter role, an actor named Rob Alter plays Tom Cruise. Theroux also enlists Scientology apostate Marty Rathbun to help recreate of a violent Miscavige freak-out in a corporate office, in which Perez becomes possessed by a bullying rage that’s truly terrifying to watch. Even in straight dramas, you’re not likely to see a scene as live-wire and treacherous as this one. (Despite witness testimony, the church denies this recreated event ever took place.)

Rathbun, who’s self-described as the onetime “baddest-ass dude in Scientology,” also provides the film’s with another fascinating angle. In his genteel manner, Theroux chooses perhaps the wrong moment to challenge Rathburn on his blatant hypocrisy: How can this former strongman be so furious when the malicious, shrieking church trolls turn against him? Rathbun’s reaction to that accusation—he goes completely nuts—reveals multitudes about the inner circle of Scientology and the headspace of its members.

Which was an insight missing in Alex Gibney’s adaptation of Lawrence Wright’s book, Going Clear. That documentary, in order to assure participation of apostates I suppose, never really challenged any of them in the way Theroux does Rathbun. Gibney tended to treat the ex-Scientologists as victims—and in Going Clear‘s worst scene, he features a whole montage of former church members laughing and crowing about the religion’s crazy sci-fi precepts…the ones that they all believed for decades. That is deeply uninteresting as journalism. Theroux dispenses with the gratuitous mocking of the religion itself (is its backstory really any weirder than, say, Noah?) and his low-key approach yields honest moments of insight about the complexities of confronting another person’s faith. His conclusions about the power of doctrine are, ironically, transcendent. And for its imagination and open-mindedness, My Scientology Movie is one of the best documentaries of the year.