Louis Theroux's My Scientology Movie is one of the highlights of this year's Sheffield Doc/Fest

Talking during a Q&A session following a screening of the film, called My Scientology Movie, at the Sheffield Doc/Fest on Saturday, Theroux said exploring the subject was a 'special thing'.

The documentary, directed by John Dower, takes a novel approach, featuring scenes portrayed by actors playing senior members of the notorious organisation founded by the science fiction writer L. Ron Hubbard. Theroux was granted no access to Scientologists, and so turned to ex-devotees for help.

But he told an audience at the Showroom: "It was crucial that we should not be seen to be taking cheap shots at Scientology, because a lot of it is odd - but religion is by its very nature odd.

"I tried to interrogate our own methods as we went along and think 'Would we do this to the Anglican church or indeed Buddishm or, if you like, Islam?'

"We're all schooled, with Islam especially because of the current climate, to exercise sensitivity about the prophet Mohammed for example, and to what extent we think things outside the religion seem slightly unusual, but to actual believers seem deeply ingrained."

Theroux added: "Notwithstanding that it's so new - because there are other new religions - Scientology is particularly unusual. It's a confluence of a number of different cultural factors to do with its involvement of UFO belief, a kind of corporate attitude to do with increasing revenue that's based on a McDonald's-style sales system, that also involves this inculcated sense of secrecy. Part of their belief is that you really need to behave as though no-one should know what you're doing. There's a sort of spy-like component to it.

"So all these different flavours - religious, corporate, UFO, self-help as well - are all combined."