God does not equal religion. If you believe it does, then I can see why you'd write off the film as preachy and religious.
This is also very much a story about faith, and not just faith in a God, but faith in anything, and what that means. In fact, I'd say that this movie has nothing to do with anything external (God, religion), and everything to do with things that are purely internal (faith, spirituality).
I find it interesting when people say the film is trying to get anyone to believe in God - you could easily take away from this film that the only reason anyone believes in God is not because he is 'real', but as a way to survive the harsh, crushing reality of life.
I was very bothered by the film during the first 30 minutes, because I did think it was going to turn into nothing but religious propoganda. But it didn't - there's more here than that, and I enjoyed it the more I spent time thinking about it. I've only seen it once, but I may pick it up to watch again and see how it plays on a second viewing. It's the type of film that could go either way, depending on how well the begininng supports the end.