CATECHISM OF THE CATHOLIC CHURCH
SECOND EDITION

Paragraphs 212–216

212 Over the centuries, Israel's faith was able to manifest and deepen realization of the riches contained in the revelation of the divine name. God is unique; there are no other gods besides him. He transcends the world and history. He made heaven and earth: "They will perish, but you endure; they will all wear out like a garment. . . . but you are the same, and your years have no end." In God "there is no variation or shadow due to change." God is "HE WHO IS", from everlasting to everlasting, and as such remains ever faithful to himself and to his promises.
213 The revelation of the ineffable name "I AM WHO AM" contains then the truth that God alone IS. The Greek Septuagint translation of the Hebrew Scriptures, and following it the Church's Tradition, understood the divine name in this sense: God is the fullness of Being and of every perfection, without origin and without end. All creatures receive all that they are and have from him; but he alone is his very being, and he is of himself everything that he is.
214 God, "HE WHO IS", revealed himself to Israel as the one "abounding in steadfast love and faithfulness". These two terms express summarily the riches of the divine name. In all his works God displays, not only his kindness, goodness, grace and steadfast love, but also his trustworthiness, constancy, faithfulness and truth. "I give thanks to your name for your steadfast love and your faithfulness." He is the Truth, for "God is light and in him there is no darkness"; "God is love", as the apostle John teaches.
215 "The sum of your word is truth; and every one of your righteous ordinances endures forever." "And now, O LORD God, you are God, and your words are true"; this is why God's promises always come true. God is Truth itself, whose words cannot deceive. This is why one can abandon oneself in full trust to the truth and faithfulness of his word in all things. The beginning of sin and of man's fall was due to a lie of the tempter who induced doubt of God's word, kindness and faithfulness.
216 God's truth is his wisdom, which commands the whole created order and governs the world. God, who alone made heaven and earth, can alone impart true knowledge of every created thing in relation to himself.