It only cost $3 million to create, but the hit prayer drama "War Room," the faith-based film directed by the Christian brothers Alex and Stephen Kendrick, is reaping huge rewards for its compelling storyline and talented cast. The movie almost surpassed "Straight Outta Compton" as the weekend's highest-grossing domestic release with its $11 million debut.

The film tells the story of a crumbling marriage that is rescued when a troubled wife sets up a prayer room, or a "war room," and begins to bow down her head in prayer. It is distributed by Sony's Affirm division and is already on course to become the Kendrick brothers' biggest hit, rivalling the $34.5 million brought in by "Courageous" and the $33.5 million generated by "Fireproof," according to News Max.

The film's box-office success is being attributed to its cast of African-Americans, attracting both black and white moviegoers to watch it. According to the Pew Research Center, African-Americans are more religious than the general US population, with nearly 90 percent of African-Americans describing themselves as belonging to a religious group. Six out of 10 come from historically black Protestant churches while 15 percent coming from evangelical churches.

For the Kendrick brothers, doing faith-based movies is a big challenge because of the heavy scrutiny they get from their Hollywood counterparts. But all their hard work appears to have paid off as theatres showing "War Room" continue to draw more moviegoers.

"Critics in Hollywood are rough with us," said Alex. "They don't understand why we make our movies or our worldview. But our target audience gets them and that's who we want to draw closer to a walk with God."

"When we were working on the plot [of 'War Room'], it just seemed more powerful and passionate when told through the perspective of African-Americans," he said. "I'm not sure it would have been as heart-grabbing if we hadn't done that."