Johnny Cash is one of the most influential country artists of all time, known globally for his musical ingenuity, lyrical depth and cross-genre popularity. But it was the country icon's deep Christian faith, spiritual boldness and hard-earned understanding of God's forgiveness and grace that defined his life.

That's according to his son, John Carter-Cash, who in an interview with The Christian Post reflected on his father's complicated life and dramatic conversion, shown in-depth for the first time in the documentary "Johnny Cash: The Redemption of an American Icon." The film is set for a three-day release in theaters on Dec. 5, 6 and 7.

"His faith was what was important to him, and it's the truth," Carter-Cash told CP during a sit-down interview.

The documentary, which was authorized by the Johnny Cash Estate and narrated by Marty Stuart, features previously unreleased footage and recordings of the "Ring of Fire" singer, starting with his humble beginnings in rural Arkansas to his reign as the Father of Country Music. It's based on the book of the same name by California Pastor Greg Laurie, who is also featured in the film.

Carter-Cash acknowledged that though his father's life and career have been exhaustively covered in literature, film and media, most publicly in the award-winning film "Walk the Line," none of them have examined the singer's faith quite like "The Redemption of an American Icon."

"I think some other filmmakers may feel like it distracts from the story or, or turns people off, but my dad was never one to let that stop him from professing what he believed in," he said.

It's been part of his mission, Carter-Cash added, to highlight what was important to his father: his relationship with his wife, June Carter, his music and his personal salvation. He sees the documentary as a "continuance of this mission."

"If it hadn't been for his faith, there was a number of times that I know he would have died," Carter-Cash said, adding that it was his father's faith that carried him throughout various tragedies in his life, from the death of his 14-year-old brother to the loss, many decades later, of his "great love," June Carter Cash.

"Throughout my early years, my parents were very close. And everything was wonderful," Carter-Cash said. "Their marriage almost fell apart in the late 1970s, early 1980s — his addiction was just as bad as it ever had been. But I watched him change his life again, I watched him go through recovery. My mother also forgave my father, and they turned their relationship back around. They were incredibly close until the end of their lives."

"It was the love that endured," he added. "It wasn't happily ever after all the time, but they were together, through it all, to the end."

Numerous artists are featured in the documentary, including Sheryl Crow, Tim McGraw, Wynonna Judd, Jimmie Allen and Alice Cooper. All reflect on the impact Cash had on their own careers and how his character inspired them.

"My dad had fans in every walk of life, from a punk rock fan in the streets of Germany to little old lady in Branson, Missouri, with a Johnny Cash record collection," Carter-Cash said. "He touched people all around the world with the magic of music and the magic of the spirit. He was unique; he wasn't like anyone else."

And as the documentary shows, Cash's life was anything but ordinary.

He left home to join the Air Force and start a family, later finding success in country music. At the height of his fame and amid a devastating amphetamine addiction, the songwriter found God in Nickajack Cave in Chattanooga, Tennessee, in the fall of 1967.

Following his conversion, Cash, who died in 2003, dedicated his time and resources to furthering the Gospel, touring with famed evangelist Billy Graham in the '70s and releasing gospel albums. His boldness came with a cost: ABC took issue with his references to his faith and cancelled his weekly TV show in 1971.

"He didn't care if he got cancelled; he stood up for what he believed. It was his nature," Carter-Cash said. "And, I mean, what did he have to lose? He'd already hit rock bottom. He knew he had a lot to give back."

The difficult parts of Cash's life — his struggles with substance abuse, marital indiscretions, including his divorce from his first wife, Vivian Distin, and battle with depression — are not glossed over in the documentary. He's presented as a complicated figure who battled demons throughout his life.

But it was his own struggles that gave him the ability to minister to others and truly understand grace. Cash performed in prisons across the country — even famously recording an album at Folsom State Prison — and publicly advocated for prison reform.

Cash saw himself in those prisoners, says his son. He wore black, earning him the monicker "The Man in Black," "for the prisoner who has long paid for his crime, but is there because he's a victim of the times."

"Having struggled and having such addiction problems and all these different issues that he had in his life, it helped him to realize that he was the same as everyone else," Carter-Cash said. "Through his hardship and letting his hardships be known, he could help other people. He had a great understanding of forgiveness and great compassion. He spoke for those who didn't have a voice."

"Dad had a lot to give in many different ways, but it was very frustrating for him, and sometimes for those around him, when he continued to fall short. But he kept getting back up and he kept finding grace, and he kept bringing people back together again."

In one recording featured in the film, Cash says that despite the difficulties he faced in his life, he never felt anger or bitterness toward God. According to his son, he also believed in living a life free of regret, instead choosing to focus on God's faithfulness throughout his life.

"He said he never had regrets. And I think there's a difference between looking back on your life and saying, 'If I could go back, I would make this choice instead,' and looking back and saying, 'I have great regrets for what I did,'" Carter-Cash said.

"I know he would change the fact that he wasn't there for my sisters during the 1960s when he was splitting up with their mother. But, at the same time, the path that he took led him to my mother, it led him to where he was supposed to be. And I'm very grateful for that."

Carter-Cash said he hopes that through the documentary, viewers gain a better understanding of who his father was: a gentle-natured artist whose faith meant everything to him.

Carter-Cash is the first to acknowledge that his father wasn't perfect; he was a sinner saved by the grace of God — and he lived with a deep awareness of that truth. That, he said, is what gives his father's life and legacy its enduring power.

"At the end of his life when he was when he was in such pain and physical pain and infirmity, he carried on and he persisted, and then he kept up his creativity," he said.

"That itself gives me sort of a creed for the way that I hope to live. He taught me to forgive and never hold a grudge. I hope my children learn from my mistakes, and that they also can live a life better than I have. And I think my father would say the same thing. He fell short every day, we all fall short every day, but he had the personal awareness of what he could do better next time."

"Johnny Cash: The Redemption of an American Icon" hits US theatres Dec. 5.

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