This parable reveals and demonstrates the force of the repentance of sinners and the greatness of God’s love towards man, and thereby serves as a summons to all who are in sin. God the Father, the lover of man, is called and referred to as a man, while his sons are the two types of men, the just and sinners….The Lord does not bestow crowns on those who are compelled to refrain from evil, but rather on those who do good by their own free choice. It is not natural goodness which is
required; the goodness which comes from free choice is that which is salutary and laudable.

From John Chrysostom, The Gospel Commentary, translated from Slavonic into English by Abbot German Ciuba (Church of the Nativity of Christ, Old Rite, Erie, Pa.)