This text is referred to as the gospel-within-the-Gospel. Here, Jesus was speaking to the Pharisees, who were mad at Him for eating with (i.e. accepting, noting unity with) sinners, tax collectors, the scum of society. One collector was Matthew; another, Zacchaeus. They worked on the Sabbath, extorting from their fellow men - yet Jesus ate with them. Today He eats with sinners too. He gives us His body and blood in the most unifying Supper of all.
In the parable-within-the-Gospel, the younger son said, in effect, "Father, I wish you were dead." But father says OK! Taking half of the inheritance, the son wastes it, then hires himself out to a citizen, literally "gluing" himself on. Since the gluee most likely doesn't want this elp, he gives a job geared to make the son quit. A Jew, feeding pigs? Strangely, the son accepts. Once starving, he decides to return to his father as a hired servant.
The village expects the father to beat his son. BUT Dad ran a long way to his son, having compassion, welcoming him back, and intervening. Thus, the father is the Christ figure - and we are both sons (prideful yet profligate). He welcomes us back, when we repent, with open arms. Therefore have mercy on your profligate siblings in Christ. For He welcomes sinners and eats with them.
Soli Deo gloria.