The moral of the movie is simple. The homeless don't need to be fixed nearly so badly as each homeless person needs to be known as a person, and every person needs a friend. It's a great moral.
Here's the rub of the movie. You can't always fix the things that make a man choose homelessness. Sure, sometimes you can do things that make room for a miracle, but when a person has chosen a life outside of the culture there's always some root cause. We like to think they just misunderstood something or had a run of bad luck, but sometimes it's nothing like that. Sometimes it's nothing anyone can explain, fix, or prevent. The co-protagonists of this movie tried everything to improve this man's life and got nowhere the hard way.
The movie asks a tough question (and answers it to its own satisfaction) that I think Christians need to answer.
Can you be a friend to a broken man, apart from needing to save him?