SPOILER - Everyone just accepts Arlen spoke to God
I found the human story in this movie to be quite well developed. You had multiple characters with painful pasts trying to find meaning in life. You had people growing to be friends and people supporting each other.
All of which did not require the 'hotline-to-God' sub-plot. Everyone in the movie, everyone without exception believed that Arlen truly spoke to God. Everyone had faith that he was telling the truth because of his comforting positive words in the book.
It was quite obvious from the first time we see Arlan that he is a sham.
In the last 5 minutes he admits that God actually really didn't speak to him at all. That he used his imagination to write his wonderful words. I imagine in the next revision of the Bible that the steering committee might add this offense to the existing commandments as one of the bad ones, but in this movie, its fine. No problem. Thank goodness is was the Christian God he was using his imagination about.
A bone was thrown to the gullible members of the audience that felt cheated of the fantasy of an author that could truly speak to the creator that maybe God had intervened in Arlen's thoughts to pass his messages of hope and love to Arlen behind the scenes. Or a more likely explanation is that Arlen is a seriously creative, empathic individual that developed his own model of God that matched the world he saw around him.
So, I enjoyed the human message in the movie but I wish they would have toned down the faith message. At the end everyone who had blind faith looked foolish for believing in his nonsense and as his punishment, he got the girl. Kind of a mess as a movie, and one in which all the characters are too gullable to care for with the exception of Arlen.