Samuel Goldwyn Films

Shia LaBeouf has starred in three straight No. 1 movies. Kirk Cameron hasn't seen his face on a multiplex screen in seven years. Guess who's the hottest ticket heading into the weekend?

Sure about that?

In terms of advance sales, Cameron's Fireproof, an ultra-low-budget marriage-minded family drama opening on about 800 screens, has smoked LaBeouf's $105 million, opening-everywhere thriller Eagle Eye.

Surprisingly perhaps, box-office experts are not surprised...

"I just think that that market is particularly aggressive in group sales," says Exhibitor Relations analyst Jeff Bock.

That market consists of churchgoers and followers of Christian groups—the moviegoers who helped make Mel Gibson's The Passion of the Christ a blockbuster, and the lesser-known Facing the Giants a fairytale success. (Made for a pittance, a reputed $10,000, the football- and God-grounded Facing the Giants grossed more than $10 million in theaters in 2006.)

Fireproof seems primed to follow those films' paths.

The Christian leader James Dobson's Focus on the Family prominently plugged the film. The Baptist Press urged readers: "Get your church behind it. Mark the weekend of Sept. 26-28 on your calendar. And go see it."

The call was heard.

Fireproof accounted for a whopping 40 percent of all advance sales this week on Fandango, the ticket service said today. Eagle Eye was a distant second, representing 17 percent of sales. (Fandango and E! Online are both owned by Comcast.)

At Movietickets.com, the story was the same. Through Wednesday, Fireproof was leading the week with 23 percent of all advance sales. No other movie, Eagle Eye included, was even in double digits.

Despite the eye-popping advance-ticket numbers, Eagle Eye, not Fireproof, is expected to be the weekend's No. 1 movie.

The LaBeouf movie's shooting for a $30 millionish opening; Bock says Fireproof, which cost well under $1 million to produce, would do well to open with $3-$5 million. (Facing the Giants bowed with $1.3 million.)

"Kirk Cameron has really established himself in the Christian community," Bock says.

A 1980s teen idol of Growing Pains fame, Cameron, now 37, has become better known this decade for his work with his ministry and TBN show, The Way of the Master. He also starred in the first two movies from the Rapture-focused Left Behind series.

This week, Cameron promoted Fireproof beyond the Christian press, including a stop on NBC's Today. And while the movie wasn't screened in advance for critics, Samuel Goldwyn Films, which is distributing Fireproof, hopes the film can build on its base.

Said Michael Silberman, Samuel Goldwyn distribution chief, in an email, "We expect the excellent word of mouth from the opening weekend audience to influence a broader audience to see an uplifting movie with a positive message about marriage."