Cliff Kinkaid discusses Tom Cruise, Scientology, Islam and Hollywood in Tom Cruise Vs. Mel Gibson. He notes and documents the favorable treatment that Scientology and Islam get in Hollywood, and thinks that the reason is that representatives of both religions will sue at the drop of a hat. He thinks Mel Gibson does not get as sanguine a welcome, noting that he had to finance The Passion himself. He thinks Roman Catholics and Christians (which he lumps together) get the shorter end of the stick because they do not sue.
I wouldn't entirely agree. Cruise was widely treated as nutty in his recent spate of appearances and spouting-offs. The only form of "Christianity," broadly defined, that much of Hollywood seems to know and/or treat with any degree of respect is Roman Catholicism. Even the non-Roman-Catholic pastor in Gibson's The Patriot talks about praying for the souls of dead men, hardly a Puritan -- or, for that matter, Christian... Biblically defined -- practice.
But I'd be hard pressed to come up with five recent, full-blooded, sympathetic portrayals of actual, card-carrying, Bible-believing-and-practicing Christians in the major media.
As to Islam, however, Kincaid's right on the money. I'd guess that the threats of both lawsuits and violence probably go a long way to explain the difference between the way in which Christians, on the one hand, and homosexuals and Moslems, on the other, tend to be treated in the public arena.