5th Sunday of Easter, John 13:31-33a,34-35
“I give you a new commandment: love one another.” –It may seem that this commandment to love is not new. Even under the Old Law, the Jews were commanded to love God above all (Deut. 6:5) and to love their neighbor as themselves (Lev. 19:18).
There are, in fact, three particular reasons why this commandment is said to be new:
First, because of the newness, the renewal, it produces. This newness is from charity, the charity to which Christ urges us.
Secondly, this commandment is said to be new because of the cause which produces this renewal; and this is a new spirit. There are two spirits: the old and the new. The old spirit is the spirit of slavery; the new is the spirit of love. The first produces slaves; the second, children by adoption. The spirit sets us on fire with love because "God's love has been poured into our hearts through the Holy Spirit" (Rom 5:5).
Thirdly, it is a new commandment because of the effect it established, that is, a New Covenant. The difference between the New and the Old Covenant is that between love and fear. Under the Old Covenant, this commandment was observed through fear; under the New Covenant it is observed through love. So this commandment was in the Old Law, not as characteristic of it, but as a preparation for the New Law.