CCC 1824 Fruit of the Spirit and fullness of the Law, charity keeps the commandments of God and his Christ: “Abide in my love. If you keep my commandments, you will abide in my love.”1
CCC 2055 When someone asks him, “Which commandment in the Law is the greatest?”2 Jesus replies: “You shall love the Lord your God with all your heart, and with all your soul, and with all your mind. This is the greatest and first commandment. And a second is like it: You shall love your neighbor as yourself. On these two commandments hang all the Law and the prophets.”3 The Decalogue must be interpreted in light of this twofold yet single commandment of love, the fullness of the Law:
The commandments: “You shall not commit adultery, You shall not kill, You shall not steal, You shall not covet,” and any other commandment, are summed up in this sentence: “You shall love your neighbor as yourself.” Love does no wrong to a neighbor; therefore love is the fulfilling of the law.4
CCC 2196 In response to the question about the first of the commandments, Jesus says: “The first is, ‘Hear, O Israel: The Lord our God, the Lord is one; and you shall love the Lord your God with all your heart, and with all your soul, and with all your mind, and with all your strength.’ The second is this, ‘You shall love your neighbor as yourself.’ There is no other commandment greater than these.”5
The apostle St. Paul reminds us of this: “He who loves his neighbor has fulfilled the law. The commandments, ‘You shall not commit adultery, You shall not kill, You shall not steal, You shall not covet,‘ and any other commandment, are summed up in this sentence, ‘You shall love your neighbor as yourself.’ Love does no wrong to a neighbor; therefore love is the fulfilling of the law.”6
CCC 2845 There is no limit or measure to this essentially divine forgiveness,7 whether one speaks of “sins” as in Luke (11:4), “debts” as in Matthew (6:12). We are always debtors: “Owe no one anything, except to love one another.”8 The communion of the Holy Trinity is the source and criterion of truth in every relation ship. It is lived out in prayer, above all in the Eucharist.9
God does not accept the sacrifice of a sower of disunion, but commands that he depart from the altar so that he may first be reconciled with his brother. For God can be appeased only by prayers that make peace. To God, the better offering is peace, brotherly concord, and a people made one in the unity of the Father, Son, and Holy Spirit.10
1 Jn 15:9-10; cf. Mt 22:40; Rom 13:8-10.
2 Mt 22:36.
3 Mt 22:37-40; cf. Deut 6:5; Lev 19:18.
4 Rom 13:9-10.
5 Mk 12:29-31; cf. Deut 6:4-5; Lev 19:18; Mt 22:34-40; Lk 10:25-28.
6 Rom 13:8-10.
7 Cf. Mt 18:21-22; Lk 17:3-4.
8 Rom 13:8.
9 Cf. Mt 5:23-24; 1 Jn 3:19-24.
10 St. Cyprian, De Dom. orat. 23: PL 4, 535-536; cf. Mt 5:24.