In today's Gospel Jesus takes
Love the Lord your God with all your heart and with all your soul and with all your strength.
Do not seek revenge or bear a grudge against anyone among your people, but love your neighbor as yourself. I am the Lord.
and unites them.
expands the loving of God to include all of the parts of the person as
his audience would have understood the human being: heart, soul, mind,
and strength. And he compresses the commandment in Leviticus to its essence.
Love of neighbor by itself is not a Christian Virtue it is philanthropy. And mere belief in God is not love of God, that is faith. Jesus tells us that the starting point must be a true love (agape) of God, and that love of God which expresses itself in things like attendance at mass and prayer.
Then we must unite that love of God with a love of neighbor. The love here goes beyond (philios) brotherly love to also agape, a love rooted in God.
For as many times as we hear the two commandments we still struggle to live them.