CATECHISM OF THE CATHOLIC CHURCH
SECOND EDITION

Paragraphs 2067–2071

2067 The Ten Commandments state what is required in the love of God and love of neighbor. The first three concern love of God, and the other seven love of neighbor.

As charity comprises the two commandments to which the Lord related the whole Law and the prophets . . . so the Ten Commandments were themselves given on two tablets. Three were written on one tablet and seven on the other.

2068 The Council of Trent teaches that the Ten Commandments are obligatory for Christians and that the justified man is still bound to keep them; the Second Vatican Council confirms: "The bishops, successors of the apostles, receive from the Lord . . . the mission of teaching all peoples, and of preaching the Gospel to every creature, so that all men may attain salvation through faith, Baptism and the observance of the Commandments."
2069 The Decalogue forms a coherent whole. Each "word" refers to each of the others and to all of them; they reciprocally condition one another. The two tables shed light on one another; they form an organic unity. To transgress one commandment is to infringe all the others. One cannot honor another person without blessing God his Creator. One cannot adore God without loving all men, his creatures. The Decalogue brings man's religious and social life into unity.
2070 The Ten Commandments belong to God's revelation. At the same time they teach us the true humanity of man. They bring to light the essential duties, and therefore, indirectly, the fundamental rights inherent in the nature of the human person. The Decalogue contains a privileged expression of the natural law:

From the beginning, God had implanted in the heart of man the precepts of the natural law. Then he was content to remind him of them. This was the Decalogue.

2071 The commandments of the Decalogue, although accessible to reason alone, have been revealed. To attain a complete and certain understanding of the requirements of the natural law, sinful humanity needed this revelation:

A full explanation of the commandments of the Decalogue became necessary in the state of sin because the light of reason was obscured and the will had gone astray.

We know God's commandments through the divine revelation proposed to us in the Church, and through the voice of moral conscience.