“The Pharisees and the scribes were grumbling and saying, ‘This fellow welcomes sinners and eats with them.'”
So Jesus told them a few stories, about things that were lost and then found, about a boy who got a little lost then found himself, came to his sense, as it were, and was welcomed back to the fold by a fond father, and finally about another who was never lost but lost himself in grumbling.
We get the point. Don’t we?
Then why do we still call the story, “The Prodigal Son”? Prodigal means spendthrift, wastrel, wasteful, reckless. There are no positive synonyms for prodigal.
So instead of focusing on the outcome of the story, about the story Jesus tells the Pharisees about themselves, the elder sons lost in grumbling, we lose ourselves in, well, grumbling. We continue to define the younger boy by the actions of which he has already repented, instead of delighting in the way that he turned himself around.
And thus and so, by our use of language, by using the title to perpetuate the cycle, we continue to identify with the grumblers, and show ourselves in need of hearing the story one more time.