IN "MACHINE GUN Preacher," truth is so much stranger than fiction that fiction eventually throws in the towel.

The movie is based on the wild, wild life of a Johnstown, Pa., man named Sam Childers, who went from meth user/dealer to fundamentalist preacher to gun-toting missionary in the Sudan.

Childers (Gerard Butler) is a different sort of Christian. In Sudan, when he turns the other cheek, it's to steady the rifle butt he's using to gun down Africans who are abducting children for conscription into warlord armies fighting over territory in southern Sudan and northern Uganda.

This is a very messy moral area - Childers is ultra-convinced of the obvious rightness of his cause (saving children), and this leads to zealotry and tragedy. Moreover, the movie also suggests that Childers may be a full-tilt, type-A individual who has replaced one addiction with another.

His first addiction is drugs. The movie's early scenes follow Childers' life as a biker-gang meth dealer, dealing and robbing (with Michael Shannon) to support his addiction and his cash flow.

This nearly destroys his family (Michelle Monaghan plays his wife). Childers though, sobers up and finds God, which becomes another mania - he builds his own church, turns to preaching, to missionary work, to a full-time passionate devotion to protecting Sudanese children caught up in brutal civil war. He's so passionate he's willing to kill anyone who threatens the refuge he constructs for orphans and at-risk children.

When does righteousness become selfishness? When does violence beget violence? Always? Sometimes?

"Machine Gun Preacher" director Marc Forster ("Finding Neverland") has said the movie is meant to steer clear of easy answers. It's meant, he's said, to be ambiguous.

But the movie feels more unfocused and half-formed than ambiguous, and glib in the way it links his biker life to his preaching life. As such, it wastes a committed performance from Butler, whose robust, slightly aggrandized screen presence should have been perfect for this larger-than-life role.

And the movie is unforgiveably vague on the details of the political/tribal/religious conflicts surrounding the civil wars in Sudan and Uganda.

Produced by Robbie Brenner, Craig Chapman, Deborah Giarrantana, Marc Forster, Gary Safady, directed by Marc Forster, written by Jason Keller, music by Asche & Spencer, distributed by Relativity Media.