We must attack the enemy’s line of communication. What we want is not more little books about Christianity, but more little books by Christians on other subjects – with their Christianity latent.
C.S. Lewis
If we were to replace “books” with “films” in this quote, I think we would be on the right track. Your faith should inform the worldview of the films you make intrinsically, not be used to have a character sell the audience on the plan for salvation. They can see through that. Honesty and truth are too important to be lain aside in the interests of a quick conversion. To do so undermines the God we strive to serve.
Source: christiantheology.wordpress.com