9 “In this is love— in this was manifested the love of God toward us, because that God sent his only-begotten Son into this world, that we may live through Him.— In this is love, not that we loved God, but that He loved us:” we did not love Him first: for to this end loved He us, that we may love Him: And sent His Son to be the Atoner for our sins: “litatorem,” i.e. one that sacrifices. He sacrificed for our sins. Where did He find the sacrifice? Where did He find the victim which he would offer pure? Other He found none; His own self He offered. “Beloved, if God so loved us we ought also to love one another. Peter,” says He, “do you love me?” And he said, “I love.” “Feed my sheep.”
Source: Homilies on the First Epistle of John (New Advent)