NOTES for Luk 15:1-32
"This son of yours," says the older son. The younger son renounced sonship by demanding his share of the estate as if his father were already dead, and by living as if there were no father, as if he were not the son of one who knows how to love. The older son did not do this; he lived with his father and did everything his father asked him to do. He may even have truly loved his father. But, as one priest said in a sermon on the prodigal son, by refusing his brother, by not wishing to call him brother, the older son also refuses the father; he deprives himself of sonship just as the younger one did before. For if the younger one is now a son, "this son of yours," and he does not consider him a brother, then by that very fact he ceases to be a son.
It follows that only lack of love for our neighbors deprives us of the possibility of being children of God. And it is precisely love that makes us His children, because love is the family trait of the saints. A saint is one who belongs to God, and God is love.