“So I think it’s a point of curiosity. I hope it doesn’t overshadow everything, but I’m not ashamed.”

Haggis severed his ties with the sect in protest against its position on gays and other issues in a letter made public on a former member’s blog, denouncing the highly secretive organisation as “morally reprehensible.”

The furore might quickly have died down, but for an explosive 25,000-word essay in 2011 by New Yorker writer Lawrence Wright that ended with Haggis musing that he had been “in a cult for 34 years. Everyone else could see it. I don’t know why I couldn’t.”

Reflecting on that period of his life, the 64-year-old Canadian recalls how Wright spent a year interviewing him and all his friends and acquaintances.

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“The entire time I had never used that word – cult. It wasn’t until the very last interview that I went, ‘Oh my God, I’ve been in a cult all this time and I couldn’t see it,’” he says. “It really speaks to how effective the brainwashing is. You really don’t see it.”

By that time Haggis was already a big name, having earned his first Oscar nod for penning the screenplay for 2004 blockbuster hit Million Dollar Baby and following up a year later with writing and producing Oscars for culture-clash drama Crash.

For those films, the father-of-four remains the only screenwriter in history to have penned back-to-back best picture Oscar winners.

Success on the silver screen came no less than three decades after he moved to Los Angeles, embarking on a TV career which earned him a string of awards for series like thirtysomething and Due South.

Haggis famously said he made Crash – a bumpy ride with several twists and turns that explores racial prejudice among a group of characters who are not always what they seem – to “bust liberals.”

He felt liberal America was complacently lying to itself that most of the racial problems dividing society had already been resolved.

More than a decade on, he clarifies that he was pointing the finger at himself as much as anyone else.

“It’s too easy to look at the racists and the white nationalists and people like that and say, ‘Aren’t they nasty people?’ Well of course they are nasty people, of course they are heinous, but there’s no film there,” he says.

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“You can do it – and people have done it, some very well – but for me I guess I wanted to look inward and see what I was guilty of.”

For someone who has earned so many of the most prestigious awards and nominations – there were further Oscar, Golden Globe and Bafta nods for Crash, Letters from Iwo Jima and James Bond film Casino Royale – Haggis is disarmingly self-effacing.

He puts the long wait for success down to having difficulty writing “compelling” stories and says the thought occurred “just about every week” that he wasn’t cut out for cinema, a doubt which he admits still plagues him.

A self-described atheist, Haggis says he hopes he has become a better filmmaker in the years since his break with Scientology.

“It’s very hard for me to look at Crash. I look at the thing and all I see is my mistakes,” he says.

This harsh assessment seems entirely too self-critical, and we remind him that Crash is considered a masterpiece. But he doubles down, insisting that its star Don Cheadle feels the same way.

“He can’t look at his old films and I can’t look at mine. It’s very hard,” Haggis says. “I don’t mind watching the ones that everyone ignored – I can watch In the Valley of Elah, I can watch Third Person – but the ones that were successful are hard for me to watch.”

While he may not be its most enthusiastic member, his unofficial fan club remains in rude health, and his enduring body of work is still celebrated on the festival circuit.

The filmmaker said he was “thrilled” to be picking up a special prize at the eight-day Evolution Mallorca International Film Festival, which starts on October 26, where Crash is taking centre-stage.

Festival founder Sandra Seeling Lipski describes Haggis as “a maverick filmmaker who exemplifies excellence, innovation, passion,” using cinema to “unify cultures and communities”.

“There is no better inaugural awardee than Mr Paul Haggis, who personifies every one of these attributes with a deep commitment to humanity and social justice,” she said.