Gerard Butler and Michelle Monaghan stopped in Dallas recently to talk about their film “Machine Gun Preacher,” based on the story of Sam Childers and his wife Lynn. Childers, who accompanied them, is a man with a checkered past—a former criminal and drug-user who spent plenty of time in prison. But prodded by his born-again wife, he had a conversion experience, and during a missionary trip to Africa was so shocked by conditions in South Sudan—where a brutal group called the Lord’s Resistance Army was destroying whole villages and turning boys into child soldiers—that he established a refuge where locals are fed and youngsters housed and protected. But controversially, he also took up arms to fight the LRA when they threatened his charges.

Butler, speaking in a distinctive Scottish brogue that he ordinarily loses onscreen, talked about the challenge of portraying a real-life person in the film and how he used the time he spent with Childers to hone his performance.

“This is a strange movie,” he said, noting the constant shifts from Pennsylvania to Africa and back again, “because it’s like two different worlds, and you jump from one to the other, which is part of the dichotomy or duality of Sam, of the story, of everything. Africa was a tough part of the shoot, but it was also where the heart of the movie was. It was exhausting, and it was the area that created most of the darkness and emotion of the movie. It was this beautiful, expansive country, and [there were] the children that are the driving force behind the movie. So I find that in Africa I had both the best and the worst times of the shoot.

“I spent a lot of time with Sam,” Butler continued. “In Pennsylvania, in his church, I watched him preach. I hung out in the neighborhood bars. By that point I kind of felt I already knew him. It’s all in his eyes—I mean, there’s a swagger, no doubt. But really it’s watching the way he talks, and seeing how he feels about things. That sparkle in his eyes quickly becomes a tear. He’s just a fascinating character.

“Sam likes to challenge people, in every way. Their religious beliefs, whatever. He likes to test people. He’s always sizing them up. With me, it was: could I extend past the realms of Hollywood? Was I really a bad-ass, like he was? I think he was also curious as to how much of a man of God I was.” The actor noted that the process didn’t faze him, however, because in moviemaking it was something you get used to: “It’s the nature of this business. Everybody’s sizing everybody up. You’re always being judged.”

In Childers’ case, however, things took an unusual turn. “At one point he put a gun on the table and said, ‘Pick it up,’” Butler recalled. “It was like ‘The Deer Hunter.’ And I picked it up, and then I started moving it around. And everyone was, like, ‘Whoa. Wait, it’s loaded.’ To this day I don’t understand why he was giving me a loaded gun. And then the next day he took me out to the gun range out back, where you can shoot up things.” Butler added that he was instrumental in adding a scene to the finished film in which Childers cleans a soldier’s rifle and when asked if he was an expert marksman, replies, “No, I just like my guns.”

Butler explained, though, that while he modeled his performance on Childers, there came a point when his own instincts had to take over.

“I spent as much time with him [as I could], just looking at him, studying him, evaluating him, just trying to take it in by osmosis,” he said. “And then walking around, imagining myself to be him, and just getting that swagger. I would listen to him all the time, I had literally thousands of interviews with Sam Childers talking about everything, and I just listened to them playing in the background. Between that and reading [his] book [“Another Man’s War”], you take all that.

“But then at some point you have to go away from that and say, ‘Okay, I’m going to use that and fly with that, but I’m not going to let it bog me down. I’m not playing Hitler or JFK, or somebody where people will say, ‘Wait a minute.’ You apply it to our script. There comes a point when you just let it all go, and you just fly.”

Asked about the moral issue some have raised concerning a preacher taking up weapons, Butler set the issue aside. “I’m playing a role,” he explained. “Sam’s doing what he does. If I start questioning the ethics of that, that’s not going to help any in approaching the character. There’s no doubt there’s lots of controversy about Sam and what he does. I kind of love that as well. I love that it brings up so much discussion.”

Butler emphasized how pleased he was that Childers appreciated his portrayal, recalling how screenwriter Jason Keller phoned him after screening the finished picture for Sam and Lynn. “He called me straight after,” Butler said. “He was so excited. It was a great moment for me as well. He said, ‘He loved it—he really loved it.’ And Lynn pulled him aside quietly at the end and said, ‘He got him. He really got him.’ That was a great moment for me.”

Butler ended by reflecting on his own career, noting that he’d recently made a film of Shakespeare’s “Coriolanus,” the play he’d appeared in—in a small part—very early onstage. “There’s many things I don’t like about myself, but one of the things I like is that I love a challenge, even one where I can make a fool of myself in front of a lot of people. Taking on ‘The Phantom of the Opera,’ or Leonidas [in ‘300’]. But this especially, Shakespeare opposite Ralph Fiennes and Vanessa Redgrave! I’m happy with how it turned out, but even if it hadn’t, I’d have been proud of myself just for jumping in there.”

Monaghan, who plays Sam’s wife Lynn, also reflected on how she got the part and prepared to play a real person onscreen. “I spent quite a bit of time with Sam, and he was able to share with me a little bit more about their story, and it was a complex story, obviously, and I was so intrigued at that point that I was going to fight hard for this one. And then I read for the role in, maybe, May or June, and shortly after I finished ‘Source Code,’ I got the role. I was so incredibly grateful; it was definitely something I wanted to be a part of because of the significance of the story—a true story, compelling and provocative. But it’s also a woman who’s right up my alley, and I was able to spend a lot of time with Lynn as well.

“I was able to be witness to their complicated relationship, and I was really able to understand the dynamics between the two of them. And Lynn answered every question I put to her—and I asked some very tough questions. She was very forthcoming. I think that first night we stayed up until about four o’clock in the morning. And finally Sam went to bed at two, and that’s when we got to the nitty-gritty, really the heart of the matter. She’s endured a lot, and is someone I consider to be the quiet giant of that family. I think she’s probably saved Sam’s life a couple of times. It has not been an easy road—they’ve sacrificed a lot. But she’s done it for the good of these children, and for me that’s incredibly humbling, to be that selfless, and potentially have a difficult marriage because of that. They have a real passion for each another. This couple loves each other through and through, and I think that’s what really binds them.

“The thing that is most special about her is her faith,” Monaghan added. “And the thing that I was most struck by was how grounded she is as a person. She’s not an emotional person—she doesn’t get angry, she doesn’t get upset. She’s very confident as a result of her faith. And that’s not like me at all—I’m a very emotional person. So it’s probably the first time as an actor that I’ve really ignored my instincts of wanting to unleash myself and be angry and upset. She’s very grounded, and it was really important for me to convey that. She’s a real person and I have a responsibility to her. Because of who she is, it’s an entirely different performance from the one I may have given.”

Monaghan said that the scene most difficult for her to play was one in which she helps Sam open a safe containing their savings from his construction business so that he can use it all for his African mission. “That really happened,” she said. “And that was a really hard one for me to reconcile. I remember that day, it was a really challenging scene for Gerry and me to do together, and for Marc [Forster] to direct. It was just a great effort—it took everything in all of us to fight against what I think human nature is. And what’s so powerful about her, is her strength. My mantra really was ‘quiet giant.’”

“We had a standing ovation in Toronto [after the film’s festival screening],” Monaghan concluded, “and to see the look on her and Sam’s faces, I can’t tell you of a couple more deserving of a standing ovation. She added: “What we really want this movie to do is to have it be an opportunity to educate yourself about that part of the world, inspiring you to do something—even if it’s writing a check. It’s going to make people talk and debate, and that’s why I think it’s an important film.”

And what of Childers? A blunt, direct fellow, he simply said: “On the overall picture, I was very well pleased with the movie. I wouldn’t be here otherwise.”

Asked whether he had qualms about selling the movie rights to his book, he replied, “Was I concerned? Absolutely. But Jason [Keller] wanted it as close as he could get to the truth.

“The action scenes at the end of the movie are amped up. I’m the first one to tell you that. But the first part of the movie—of who I was thirty-some years ago—was not amped up at all. In anything, they left out who I truly was. I wasn’t a good person.”

And for Childers the purpose behind “Machine Gun Preacher” is far greater than how he’s portrayed. “It’s about motivating people around the world,” he emphasized. “And the big thing is, I hope people who see the movie who are in the world and of the world will see that if I can change, they can change. And it gives me a platform to stand up and tell people to educate yourself about what’s going in Sudan and Darfur.”