Gerard Butler stars in “Machine Gun Preacher,” a movie based upon the real life exploits of Sam Childers, a gangster turned preacher, directed by Marc Foster.

“Machine Gun Preacher” tells the life story of Sam Childers, a drug-dealing biker turned child-saving soldier and teacher of the word of Christ. And while Childers’s transformation has radically changed his views and lifestyle, it’s not hard to imagine that the man in the Harley Davidson cutoff vest with a toothpick hanging from his mouth was once someone completely different, a man who might not have approached preaching or social action with a 10-foot pole.

“I was an awful person,” he says. “I did a TV show here not long ago, and when they interviewed me they said, ‘Sam, you’ve rode with about every motorcycle group out there. You’ve run with the worst of them. Who was the meanest person you have ever known?’ I started to cry because I didn’t know anyone meaner than me. I was probably the meanest person you would have ever met 30 years ago.”

He continues, “I was not a tough guy. There’s a difference between a tough guy and a mean guy. And I was mean. [The movie] didn’t even show a fraction of who I really was 30 years ago.”

That’s quite an admission, given that actor Gerard Butler in Marc Forster’s new film depicts Childers abusing his wife, neglecting his child, engaging in illegal drug trades, and even stabbing a hitchhiker. But Childers has put all that behind him, he says. His transformation was inspired by a harrowing bar fight that made him realize that if he continued in his current ways, he could die with no good deeds to his name.

“I was in a bad bar fight in Orlando, FL, that turned into a shootout. I almost got killed. When I went home that night as I was driving I made up my mind: ‘I’m changing.’ I got home, went to bed, and the next morning I told my wife, ‘We’re moving.’ ... I said, ‘Somebody’s gonna kill me, and I ain’t got a problem with dying—but I’ve got a problem with what I’m gonna die for.”

So Childers and his wife moved back to his home state of Pennsylvania. “And it was four years ... until I accepted Christ,” he says.

With his spiritual awakening came a new motivation to do good. As the film shows, Childers then went to East Africa, where he witnessed the atrocities that were taking place in Southern Sudan, committed by warlord Joseph Kony and the Lord’s Resistance Army (LRA).

Working to ameliorate the situation, Childers began to develop a reputation in the region. He not only built an orphanage in Southern Sudan and began rescuing and feeding hundreds of children, but he joined the Sudanese soldiers in their military combat against the rebels. He became the “White Preacher”—or the Machine Gun Preacher.

Eventually, NBC Dateline caught word of Childers and featured him in an episode; that inspired Childers to write a book, “Another Man’s War.” He was soon approached by screenwriter Jason Keller for rights to an adaptation.

Childers was at first hesitant. But Keller wouldn’t give up. “He wanted to write the story. So he kept being persistent with me, and then when I O.K.’d him to do the script he basically moved in with me for a year ... He even went further than that—he went to Africa. He interviewed the children, interviewed the soldiers. He went on the actual grounds and stayed for a week and a half at the orphanage. And at that time Marc Forster, the director, did also.”

Now, Childers finds himself grateful for the film. “It’s giving me a platform to speak out on the real truth, and it’s inspiring everyone else to also do something about it,” he says, noting that things in Sudan are much better now than they were pre-2001. Southern Sudan gained its independence in July, and much of the persecution has quieted—but the real problem now is in Darfur.

“We have to remember,” Childers says, “these children are having lips cut off, ears cut off, being cut in half, raped—the worst thing you could think of in your mind is what’s happening to these children. So we have to remember that, in Darfur, it’s still going on.”

And Childers is determined to save children wherever they need saving; his efforts have expanded into Ethiopia, Uganda, and will soon begin in Somalia. “Everywhere we go it’s about helping children,” he says.

Since his early days travelling to and from Sudan on his own, things have certainly changed for Childers. He has founded a non-profit organization called Angels of East Africa, which is currently run by his daughter.

“It’s not about ‘Machine Gun Preacher’ anymore. There’s a lot of other people on with us,” he says. And that title itself—though tattooed on his right bicep—he calls a “marketing tool.”

“It’s not all about violence with us either. I’m very big into education,” he says, citing the fact that he’s built schools, restaurants, and Sudan’s only library as part of his work.

Childers still participates in military combat in East Africa, where he spends about seven months out of every year. He is aware that many feel his contribution to the violence is not the best way to get involved in the situation, but he stands by a line from the movie: “Why don’t you fight the evil in this place your way, and I’ll fight it in mine?”

“You need to run your non-profit the way you do it, and leave me alone,” he says. “I’m not asking for you to come in and structurally form my organization. But I have saved over 1,000 children. I feed right now 3,000 to 3,500 meals a day. I’ve got to be doing something right.”

—Staff writer Abigail F. Schoenberg can be reached at aschoenb@fas.harvard.edu.