The trouble with biographical motion pictures is that, for the most part, the very reason that they exist is because they're a variation on stories we've seen before. Whenever anyone says, "What an amazing life he/she has led! That'd make a good movie!" the logic at work is that the story seems cinematic, and the reason it seems so is because it conforms to the kind of story arcs--hitting bottom, making one's own way in the face of adversity, triumphing over the odds, and so on--that have become boilerplate. The truth of the matter is, the fact that someone's life could be a movie doesn't necessarily mean that it would be a good one.

Which brings us to Machine Gun Preacher (a title that continues to rankle; whatever root it may have in the real story, it makes the picture sound as though it should be playing the lower half of a grindhouse-revival double-bill, alongside Hobo With a Shotgun). It is, as the opening titles inform us (immediately following the title, in fact), "based on the life of Sam Childers," and it is an extraordinary story; Childers was a convicted felon and all-around roughneck biker who found God, built a church, and ended up pouring his time, energy, and money into an orphanage he built in Sudan.

He is played by Gerald Butler (who also executive-produced), and the film begins with his release from the clink, at which point he is disturbed to discover that his wife (Michelle Monaghan) went and got religion while he was locked up. Sam's not hearing it, and the opening sequences are an almost-comical overload of his bad behavior: booze, drugs, broads, gun, and blood. (Though the film stacks his sins in a style creeping up on Reefer Madness territory, these scenes are done with enough grim realism and profanity to ensure the R-rating that will keep away much of the audience that will buy what follows.)

The set-up scenes are both overdone and overlong, and while the clearly devout picture is admirable for taking its religion seriously, there are parts of it that amount to just sitting in church, whatever that means to you. Most moviegoers will just be waiting for him to get over to Africa and start saving some kids and shooting some guns, which the picture portrays in just about equal measure. Director Marc Forster, whose credits include Stranger Than Fiction and Monster's Ball, stages the events crisply, though there are some thoroughly peculiar transitions (my audience giggled, for example, when Forster faded from some hot-and-heavy foreplay into a serious church scene; the incongruity is just too much). And the performances are good--Butler's got a convincing earthiness, and you believe his passion (even when it is stated in hoary lines like "Truth is, helpin' you kids is about the only good thing I've ever done in this life"), while Monaghan, though stuck in a small and rather thankless role, uses her gin-soaked voice and fiery eyes to give it life and texture. As Sam's best bad-boy buddy, Michael Shannon indulges in a bit too much eye-popping early on, though he's got a gentle comic touch in a bedside scene, filling in with his friend's daughter (Madeline Carroll) in Sam's absence. An actor (previously unknown to me) named Souleymane Sy Savane is beautifully understated as Deng, Sam's point man in Sudan.

But the simple-mindedness of Jason Keller's script is just too much for the picture to bear--and that's not just meant politically (lest we forget, other American evangelical interventions in Uganda have had decidedly less uplifting results). The compactness of the events is frequently hard to swallow--a kid dies, Sam fights back, and the child soldiers they're fighting are immediately on his side. Sam's daughter asks about a limo for her school dance at the exact moment he gets bad news from Africa. The young child terrified in the grisly and scary opening waits to make his emotional connection with Sam until the older man's darkest hour. A humanitarian aid worker exists only to be spiteful and second-guess Sam, who of course must then save her life. And so on.

There is a section, late in the film, where Sam's frustration becomes so desperate and all-encompassing that it begins to push him back into some darker places--and we lean forward a bit, because now the picture is getting interesting, going into territory we've not been in before. But that detour aside, the air of familiarity and predictability keeps Machine Gun Preacher from making much of an impression. As the end credits roll, we see documentary footage and photos of the real Sam, the real Deng, and Sam's wife and daughter. Hate to say it, but I'd have rather seen that film than this slicked-up, dramatized one.

Jason lives in New York. He holds an MA in Cultural Reporting and Criticism from NYU.