Because the only thing worse than aggressive Christianity is passive-aggressive Christianity.

"The Ten Commandments" and "Ben Hur" were all-time classics regardless of their Christian content because they were edgy, hard-hitting, and at least quasi-historical. They came before the "new wave" of post-modern Christianity, the watered-down Christianity of Sherwood Baptist Church, Jars of Clay, and the Purpose-Driven Life; the kind of "self-help" Christianity that wallows in its own simpering sentimentality, and whose sole focus is making oneself feel good while using Christ as the backdrop.

Despite being corporate-driven, film makers often avoid corporate Christianity not necessarily because they're anti-Christian, but because they don't want to deliver something so smarmy to "mainstream" audiences that it alienates them.

Fair go! Jars of Clay aren't about feeling good. I'm not sure you're familiar with their music. Their music is rather melancholy with hints of hope. There was an honesty (at least in the first few albums) that wasn't found in much of Christian music (at least in the pop/rock genre) at the time. Jars of Clay's music reflects the band members' understanding that life is a real struggle at times. The hope they point to, in that darkness, is found only in Christ and his sacrifice. They make that clear. I'll give you the other examples though. They're very much about self-help.

If movie-makers were trying to avoid smarminess in VDT, they failed horribly. It was easily the most platitude-laden Narnia movie we've had yet. In fact, I would argue that Hollywood has no problem with delivering smarmy Christian movies. They fit right in with the smarmy secular movies. 90% of the movies coming out with any sort of moral or ideal to them boils down to the same tired old cliches: believe in yourself, chase your dreams, yada yada yada.

I think the answer is quite clear: movies are made to make money.

While 75% of Americans identify as Christians, we all know that if you actually look at scriptural evidence for Christians the number is probably closer to something like 2%, but of course the true answer this is unknowable to man, and really shouldn't even matter to us anyways. The point is, you've got all the Christians borrowing from postmodern relativist morality, and Lady Gaga throwing in her theology ("it doesn't matter if you love him, or HIM...I'm beautiful in my way, 'cause God makes no mistakes...I was born this way") and you end up with a mixture of 700 million pseudo-Christians who've never picked up a Bible in their life. I know many of them. So what is really going to sell? The salt/light mixture of Lewis' intent, or the watered down false prophecies of mega church ideologies? Not that I have anything against mega churches in and of the idea of one.