What a surprise. Its grindhouse title notwithstanding, "Machine Gun Preacher" is a genuine drama. While there are a few scenes that could fit in a Rambo movie, the film intelligently explores the impact of religious conversion on a man of explosive impulses.
The story is inspired by the experiences of Pennsylvania ex-con Sam Childers (portrayed by Gerard Butler), a violent biker/drug dealer whose wife, Lynn (Michelle Monaghan), found religion while he was in prison. She drags the reluctant ex-con to services. His baptism introduces Sam to a Christian community of fellowship and affirmation, and a new kind of addictive high.
With his substance abuse behind him, Sam establishes a successful construction business and begins building the American dream life. He becomes a better man, helping his onetime partner-in-crime Donny (Michael Shannon) to reform his life.
Then Sam visits Sudan and has a revelation. He becomes consumed by the plight of child refugees, Christian southerners pushed out of their villages by northern Muslim raiders. He tells Lynn that God has spoken to him, and returns to build a modest orphanage. This puts him in conflict with the murderous local warlords, who abduct young boys and brutally train them to be soldiers.
Sam returns to his real life in Pennsylvania, where he has established his own small congregation, urging his followers to support his crusade. His trips to Africa grow longer, his family more distant. Sam's temper flares when one wealthy parishioner tithes less for Africa than Sam expects. Every standard American luxury that Sam worked for now appears self-indulgent and decadent. He can't understand why the whole world doesn't share his fervor. Sam's sermons become bursts of street poetry that garble the standard Sunday pieties. "God doesn't want sheep -- he wants wolves."
Ultimately Sam takes up arms against Joseph Kony's brutal Lord's Resistance Army, itself a nominally Christian guerrilla organization. Sam becomes a zealot in a war with no end in sight. This avenging-angel antihero engages in firefights with the LRA that echo earlier scenes of Sam's shootouts with rival pushers.
Butler delivers a grand performance in a multifaceted part. Director Marc Forster ("Monster's Ball," "Quantum of Solace") shows violence with unflinching candor, and weighs the good that religion does against the bad, leaving final judgment to the viewers. The last scene, an aerial shot that makes Sam a speck on a vast African plain, suggests that Sam is a mad prophet wandering the desert alone. It's a fitting climax for a sharply intelligent, disquieting and ultimately inconclusive commentary on God's will and man's frailties.