Hollywood folks seem particularly vulnerable to this silly siren song.
Hollywood will fall in love with any nonsense that mocks Christianity. They loved producing "The Last Temptation of Christ" and nurtured it like a baby, but Mel Gibson had to produce "The Passion of the Christ" with his own private money because no one in Hollywood would touch such a pro-Christian film.
Dan Brown's apparently plagiarized anti-Christian schlock was a natural for Hollywood.
The main problem is that it's pushed as being the truth. I've had a co-worker and a student assistant both tell me that the story is technically fiction but it's "based on the truth". They insist that Brown conducted years of research and "proved" that Christ didn't die on the cross, married Mary Magdalene, and that Christianity has been fake from the very beginning. But instead of writing a "boring" non-fiction book about his findings, he decided to produce a more "exciting" story that's fictional but based on the true story he uncovered. The book is promoted in a manner that lures people into believing that it's based on the truth, and I'm sure the film will be pushed in the same way.
Needless to say, a film "exposing" Islam, Buddhism, Hinduism, or any other religion as being a "fraud" wouldn't be touched by Hollywood with a ten foot pole.