I went into this film fully expecting to hate it. A friend of mine begged me to go to it, but I otherwise would have avoided it. Without going into any spoilers, the whole plot will be more comprehensible if you have some familiarity with Catholic teachings, but a general knowledge of Christian lore will probably be enough to enjoy the film. It does contain some windy dime store philosophy, but I don't think it really gets in the way too much. Writer and director Smith has a real knack for writing dialogue and creating some amusing situations. Even if they are occasionally predictable, it somehow didn't bother me as such things usually do. Zealots should steer clear, but I recommend it to all others.
