Catechism of the Catholic Church
2112 The first commandment condemns polytheism. It requires man neither to believe in, nor to venerate, other divinities than the one true God. Scripture constantly recalls this rejection of "idols, [of] silver and gold, the work of men's hands. They have mouths, but do not speak; eyes, but do not see." These empty idols make their worshippers empty: "Those who make them are like them; so are all who trust in them." 42 God, however, is the "living God" 43 who gives life and intervenes in history.
2113 Idolatry not only refers to false pagan worship. It remains a constant temptation to faith. Idolatry consists in divinizing what is not God. Man commits idolatry whenever he honors and reveres a creature in place of God, whether this be gods or demons (for example, satanism), power, pleasure, race, ancestors, the state, money, etc. Jesus says, "You cannot serve God and mammon." 44 Many martyrs died for not adoring "the Beast" 45 refusing even to simulate such worship. Idolatry rejects the unique Lordship of God; it is therefore incompatible with communion with God. 46
2114 Human life finds its unity in the adoration of the one God. The commandment to worship the Lord alone integrates man and saves him from an endless disintegration. Idolatry is a perversion of man's innate religious sense. An idolater is someone who "transfers his indestructible notion of God to anything other than God." 47
English Translation of the Cathechism of the Catholic Church for the United States of America © 1997, United States Catholic Conference, Inc.