If you want to make this story about god, then you need to go the whole way with it.
"If the prodigal son had never come home, he would have been on his own."
The prodigal son not coming back home. If the father is god, and the son, man, this is not where the story ends. Not only would the son be on his own, he would have been punished and damned for all eternity. Have you forgotten about 'hell'??? Now theres some big love for ya!