(CP) When Mel Gibson was first approached to play in "Father Stu," a Mark Wahlberg film about a boxer-turned-priest, he was sceptical.

"It didn't sound like it was going to work," the 66-year-old Academy Award-winner told The Christian Post.

But after reading the script, Gibson said he was hooked.

"I read the screenplay and it made me laugh, and then it was emotionally very effective," he said. "This one smelled good, and it looked good, and it was great, it was funny. It was a film that wasn't preaching to the choir and it wasn't over saccharin, and just had a lot of a big splash of reality in it."

"Father Stu," hitting theaters just ahead of Easter Sunday, is based on the true story of amateur boxer, Stuart Long (Mark Wahlberg) who moves to Los Angeles dreaming of stardom. There, he meets a Catholic Sunday School teacher, Carmen, (Teresa Ruiz), and begins attending church in an effort to win her over. After surviving a terrible motorcycle accident, however, Stu begins to rethink his life.

Determined to help others, he decides to become a Catholic priest, ignoring the reservations of church officials and his agnostic parents (Gibson and Jacki Weaver). Despite a devastating health diagnosis and other challenges, Stu seeks to follow God's calling on his life, inspiring countless others along the way.

Gibson stars as Bill Long, Stu's long-estranged, foul-mouthed father. A truck driver, Bill is battling his own demons, having fled to Los Angeles after Stu's younger brother died. He and Stu initially have an antagonistic relationship; one defined by resentment, anger and bitterness.

But their story arch, Gibson said, demonstrates that redemption is possible for even the most flawed people.

"I was kind of being the devil's advocate here in the film because I'm the agnostic guy who's like, giving [Stu] hell for doing what he's doing," he said. "The beauty of that is that he's eventually won over by the purity of his son and how it cuts through all the judgmental baloney and it just goes straight to the heart, straight to the soul."

"There's a transformation needed in all of us on a daily basis, I might add," the actor said. "I wake up pretty grumpy, and I've got to find ways to not be that way. It's a continuing struggle."

And watching "Father Stu" with an audience for the first time made him realize just how impactful it truly is, Gibson shared.

"It works," he said. "I got choked up."

"Father Stu" is a passion project for Wahlberg, who put his own money into financing the film. Gibson's longtime partner, writer-director Rosalind Ross, wrote the script for "Father Stu," and the film will mark her directorial debut.

Gibson is no stranger to films that both challenge and uplift audiences. In 2004, he produced, co-wrote and directed "The Passion of the Christ" starring Jim Caviezel. The film, which was nominated for three Academy Awards, had a worldwide box office gross of $610 million, making it the highest-grossing R-rated film and highest-grossing independent film in history.

Caviezel previously revealed that a sequel is in the works and said he'd received a third draft of the script from Gibson.

Like "The Passion of the Christ," "Father Stu" is rated R. With language and some crude jokes littered throughout the film, "Father Stu" is not a faith-based film — something Gibson has repeatedly stressed. Yet, it's rife with religious imagery and biblical themes. Redemption, forgiveness and grace are woven throughout the storyline the actor described as "expertly penned."

Though he, unlike his "Father Stu" character, is a man of faith, Gibson said he's aware of his own flaws and need for grace. The "Passion of the Christ" director reflected on how "Father Stu" doesn't paint a rosy picture of the Christian life; rather, it highlights God's sovereignty and grace amid suffering.

"I've been taught from a young age that we're flawed, and you're going to make mistakes," he reflected. "We're broken, and we need help. Usually, the best way to get help is to ask for it. And well, who do we ask? We're asking something better than us. And the minute you acknowledge that there is something better than you, you might get something that resembles humility, which is really the key to the whole thing."

"In this day and age, it's easy to live in your ego, which is kind of what this film is about," Gibson added. "It's about a guy who was living in his ego, and managed to sort of make that leap of faith to understand that there's something greater than he is. And that made him humble and it made him grateful, even in his infirmities."

With decades of life under his belt, Gibson is the first to acknowledge he hasn't always gotten it right — but encouraged the next generation to "stick" to their "convictions" even though it's "hard" in an increasingly polarized society. Father Stu, who died in 2014, exemplified this truth in a tremendous way.

"Sometimes you're presented with choices or put in places that are very difficult, and some of those choices are hard," he said. "You just have to examine your own conscience and take the right road, I think ... there's no right way; there are a million wrong ways, and you just have to eliminate those or just use your best discernment to get through it."

"But it's hard, man," he added. "Life's hard. But we're all going. We've all got a boulder we're dragging."

"Father Stu" hits theaters in the US April 15.

© The Christian Post