Catechism of the Catholic Church

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. (1062)