Inheritance is central to the story. The older brother is working to increase the value of the estate, because he’ll inherit half one day. The younger brother asked for his half up front in cash and wasted it. The older brother is pissed because he cares about doing the right thing, and he’s not especially rewarded for doing it when others don’t.

There’s another story in the Bible about this, the vineyard workers. Workers are hired for the day with the promise of a day’s wage. Some are hired in the morning, others at noon, afternoon, and an hour before dark. The morning workers are angry because everyone got paid the same, and the vineyard owner reminds them that they were paid fairly, and that they should not let what others receive damage their contented-ness.

Christianity’s emphasis of forgiveness and full welcoming has been criticized by many austere and rigorously just religions and philosophies.