By Clark Collis
June 03, 2014 at 03:42 PM EDT

There are plenty of fantastical villains in this year’s summer movies. But in terms of horribly believable evil, it will be hard to top the performance of actor Gene Jones as “Father” in director Ti West‘s thriller The Sacrament, which lands in cinemas this Friday.

Inspired by 1978’s infamous Jonestown mass suicide — in which almost a thousand People’s Temple cult members died from cyanide poisoning — the movie stars Jones as an avuncular-seeming church leader who reveals a far darker side when he is investigated by a pair of fictional VICE journalists (AJ Bowen and Joe Swanberg). “He believes absolutely poisonous things, but he would do anything for you,” says Jones of his character.

Jones declines to give his age — “I’m still fooling people” — but it is fair to say he is something of a late bloomer. The Louisiana native spent almost thirty years acting in theater before getting his big screen break when he was cast by the Coen brothers in No Country For Old Men. His role? The gas station attendant who finds himself involved in a potentially lethal game of “heads or tails” with Javier Bardem’s devilish Anton Chigurh. “People still stop me on the street and start saying Javier Bardem’s lines, and want me to say my lines,” he explains. “Of course I’ve long forgotten them.”

Casting directors didn’t forget Jones, who subsequently scored roles in Louie, House of Cards, and Oz the Great and Powerful. “I’m in it because Sam Raimi liked my voice,” says the actor of the latter film. “I’m the barker at the Wild West show in that wonderful opening shot where a camera on a crane travels thorough the middle of a small town carnival. I loved working for Sam Raimi. He was a very nice guy.”

Although The Sacrament is based on the Jonestown tragedy, Jones said he did not research the real-life leader of the People’s Temple, Jim Jones. “Ti’s first idea was to to produce this as a television miniseries that would have been 8 or 10 hours long,” says the actor. “If we’d done that of course I would have researched Jim Jones. I would have found out what he had for breakfast, where he got his drugs, how he ran his business. But our script happens in one day, and it is not a typical day. So what I tried to do was create a character who was avuncular and kindly, somebody who was so kind and trustworthy and sweet, you would follow him anywhere. I tried to create a person who was evil but was not mean.”

At the heart of Jones’ performance is a ten minute-plus interview between Father and Bowen’s journalist, conducted in front of the cult leader’s congregation. “We did many takes, but we got it on the first take,” says Jones. “Much of what you see in the film is from that first take. It’s almost 12 minutes in the film and it was all written. There was no improv in that except from the parishioners, who began to talk back to me, which I loved. I could get them to agree with me, and say ‘Amen,’ and say ‘Oh no!’ Their stuff was improvised and it was absolutely different every time we did it. But AJ and I followed the script and the original version of it was 17 minutes long.”

Jones continues to make up for lost time: The actor recently starred in a horror movie called Dementia — “It’s about an old guy who is terrorized by his home health care aid” — and will also be seen in the forthcoming Robin Williams comedy, Merry Friggin’ Christmas. “It’s a little one-scene role, but a very nice scene,” he says. “Again, I’m an old guy at an out-of-the-way gas station. My secret mission was to make Robin laugh. I wound up making him laugh four times, so I was proud of that.”

You can see Jones as Father in the Sacrament clip below.