WARNED off on social media, followed for hours by a mysterious white SUV, silently filmed by Scientology devotees, hit with an avalanche of legal letters and with the police called on him at least twice, filmmaker Louis Theroux kept his humour, self-effacing courtesy and his nerve intact.

Then he put it all in his Scientology documentary.

And despite the roadblocks put before him as he made Louis Theroux: My Scientology Movie. Theroux says he still finds parts of the controversial religion oddly seductive.

“One of the things I have always enjoyed about Scientology is their proactive approach to journalists who are covering them,” Theroux said as he put the finishing touches to his Scientology doco, after learning the powerful religion had said it was making its own documentary on him.

“In an odd way it’s kind of a privilege to feel as though I’m on their radar.”

The documentary reveals a man very much on Scientology’s radar, as Theroux, who has been fascinated by the religion for years tries to see it from the inside.

Denied access to Scientology’s LA headquarters and interviews with Scientology leader David Miscavige — who has done just one TV interview since he took charge in 1987 — Theroux instead speaks with high-profile former members such as former second-in-command, Mark ‘Marty’ Rathbun — now viewed by the religion, which firmly denies any claims he makes about it and his 22 years in it, as a suppressive person.

“I was the baddest-ass dude in Scientology,” says Rathbun.

He left the church in 2004, and Theroux’s cameras chronicle his harassment by squirrel busters as the doco unfolds.

Theroux recruits actors to replay incidents people claim they experienced with high profile members such as Tom Cruise and Miscavige — and films the whole process, including auditions.

The result is confronting, part scary, part unsettling, part humorous, part haunting, part documentary, part feature film. And total Theroux.

In trying to portray what it feels like to be a Scientologist, he also exposes what it feels like to not be one but to be asking questions about it, as his every attempt to infiltrate the religion and talk to its members is rebuffed.

“In the course of making the film I came to believe I was being tailed by private investigators, someone in Clearwater, Florida (Scientology’s spiritual mecca) attempted to hack my emails, we were filmed covertly, I also had the police called on me more than once, not to mention a blizzard of legal letters from Scientology lawyers,” Theroux said.

He maintains his self-effacing demeanour and humour when some would be rattled.

When his attempt to hand-deliver a letter to Miscavige via the security office outside Scientology’s so-called international base in Hemet, California ends with police being called amid claims he’s on private property, Theroux calmly argues his case as a security guard silently films him.

As the standoff ends, and Scientology church official Catherine Fraser returns to the car, with both Theroux’s and the mystery cameraman’s cameras still rolling, Theroux says “what’s your name. Are you in the Sea Org?”

When a similar encounter later in the documentary begins with security floodlighting springing to life outside a razor wire fence around the compound as darkness falls, Theroux observes “that’s quite helpful”.

As he is again told he’s trespassing and he needs to leave, he offers his filming permits, insists he’s on public property, then asks Fraser’s silent cameraman “are you filming a documentary too”.

The argument as Fraser demands Theroux stop filming and he says he will turn off his cameras when she turns off hers would be farcical if it wasn’t so creepy.

In another cat-and-mouse incident Theroux turns his iPhone camera on another woman and man silently filming proceedings outside the studio Theroux’s actors are filming in. He asks what they are filming, and their names, politely pressing the point and asks them “are you making a documentary as well?” until they eventually walk off, with her accusing him of harassment. He replies with a plaintive “come back”.

Louis Theroux: My Scientology Movie will be released around Australia in selected cinemas from September 8 — for one week only — ahead of Theroux’s Australian live tour later in the month.