You might suspect that Matthew Chapman likes to stir up religious controversy because it's his birthright.
The filmmaker/author/journalist is, after all, the great-great-grandson of Charles Darwin, the naturalist who shook the Christian world with his theory of evolution.
But it was a closer relative who inspired Chapman to write and direct "The Ledge," which plays at Sundance in Ogden on Sunday.
"My initial interest in religion came not from being Darwin's great-great-grandson, but having an uncle who is gay," said Chapman, 60, a British-born filmmaker who makes his home in New York City.
"The film is dedicated to my uncle, Dick Chapman. He and his boyfriend have been together for 50 years. Growing up in England, where homosexuality was illegal, I watched these people I loved dearly suffer a great deal. When I was about 10, I began to wonder why anyone would care what these two kind, civil adults would do in their own home.
"I began to think: What was the motivation for this hatred I saw so close? It became obvious to me that the only way this hatred could be made respectable, if you like, was by a literal reading of the Bible. That was the source of my emotional issues with religion."
"The Ledge," which Chapman wrote and directed, is a thriller about what drives two men. One is a young hotel manager, Gavin (actor Charlie Hunnam, "Queer as Folk," "Sons of Anarchy"), preparing to jump to his death from a high-rise building.
Called in to talk Gavin off the ledge is police detective Hollis (Terrence Howard, "Iron Man," "Crash").
Gavin, an atheist, is confronted by Hollis, a man of faith, but as they talk, both discover that neither is sure life is worth living.
But there's a twist:
"The thriller aspect of the film is about the fact that Charlie, the nonbeliever, does not want to jump," Chapman said. "He's being forced to as a test of his nonfaith. Unless he jumps, someone else will suffer terrible consequences."
Chapman didn't want to give away too many secrets, but did say that Charlie is a straight character living with a gay roommate. The gay roommate is being persecuted by a religious fundamentalist neighbor (played by Patrick Wilson, "Morning Glory") who considers homosexuality a horrible sin. Liv Tyler plays the neighbor's wife.
"It's the homophobic remarks of the fundamentalist that triggers the whole movie," Chapman said.
The film may explore issues, but it does not get preachy, the director said.
"It's not an eat-your-broccoli type movie," Chapman said. "I've also found that it engages people as a thriller, and that people get very emotionally moved by the story."
When Chapman moved to America in the 1980s, he said, Darwin's theory of evolution was under attack by creationists.
"I was kind of intellectually offended," he recalled. "I went on a sort of journey, really, into parts of America where this kind of thing goes on."
He wrote two nonfiction books during that period, and one was about Dayton, Tenn., where the Scopes "Monkey Trial" took place. "Trials of the Monkey: An Accidental Memoir" is the book. Then, in 2005, Chapman covered a trial in Pennsylvania.
"A group of fundamentalists had taken over a school board and tried to have creationism taught in science class," he said. "Eleven parents sued over separation of church and state. I've seen a lot of this stuff, and my film is a dramatic outgrowth of these interests."
Chapman said he's excited about Sundance, and plans to stay for the whole festival, attending each of his film's screenings, including Ogden's. He hopes audiences will be entertained by the film, and maybe even leave questioning beliefs they have simply accepted in the past.
"I think everybody should question everything all the time," he said, with a laugh. "I think it's fascinating how acceptable it is to take a 5-year-old child and teach him to believe, without question, things for which there is no evidence."
* "The Ledge" (101 minutes, USA), 3:30 p.m. Sunday
Watch a Sundance artist interview with Matthew Chapman