The greatest commandment is clear: “You shall love the Lord your God with your whole heart.” The second greatest commandment is equally clear: “You shall love your neighbor as yourself.” What is not clear, perhaps, is what these commandments mean.
The juxtaposition of these two commandments, both chosen from the Hebrew Scriptures, would seem to clarify at least to some extent what it means to love God: one way we humans express our love for God is by loving our neighbor.
Today’s liturgy attempts to clarify the matter of loving one’s neighbor by another juxtaposition, preceding the Gospel with the passage from Exodus about treating justly the most vulnerable people in society.
The implication is that loving our neighbor means more than being kind to our friends and relatives, or to the person who lives next door. Loving one’s neighbor means doing right by any widow or orphan: seeing that the hungry are fed and the homeless sheltered, that the poor have their basic needs met, that the unemployed do not suffer from want, that the young are educated and the old are cared for.
To do less is to fail in our love for neighbor. To do less is also to keep us from singing with joy: “I love you, Lord, my strength.”
The commandments to love God with all one’s heart and to love one’s neighbor as oneself are the heart and soul of Christian morality. ... These commands point out the path toward true human fulfillment and happiness.
They are not arbitrary restrictions on human freedom. Only active love of God and neighbor makes the fullness of community happen. Christians look forward in hope to a true communion among all persons with each other and with God.
U.S. Bishops, Economic Justice for All:
The Responsibilities of Social Living, 1986:64