And it doesn't have to be either /or (not that that's what this particular poster is implying). I am a Christian, believe in God, etc. and read the books about a year ago before all the huff and puff about the movie. When my son is older (currently 10) he can read the books if he choses to do so. He loves mythology, Harry Potter, and most fantasy. He asked my why people are boycotting the movie and I told him, in my opinion, it's because some people fear that children will confuse what goes on in fiction with what they are taught in their faith. His answer is then most people underestimate a child's faith.
In my opinion, historically (ironically including Phillip Pullman) that it is many (not all) of those children who are banned from "outside information", who aren't allowed to read, study and think about views other than their own, who will turn on the faith that they are raised with in the end.