The worship or paying of divine honors to a false god as represented by some image or idol in which he is believed to be present. Idolatry is an offense against the virtue of religion and a direct violation of the First Commandment. It is also opposed to charity and faith: to charity, because it would deprive God of the supreme sovereignty that is His; to faith, because it is a denial of the truth that faith professes. This opposition to faith is manifestly evident when the external act of idolatrous worship proceeds from an inner conviction, or opinion, or suspicion, that the idol is adorable, because such a state of mind is radically incompatible with faith in the one true God. But there is opposition to faith even if the act is only externally simulated in conformity to custom or law but without internal belief in the false divinity or desire to honor it, for it is a transgression of the precept of divine law obliging men to confess their faith externally and under no circumstances to deny it (Mt 10.32–33). How abhorrent even a pretense of idolatry is to the Christian conscience is apparent from the reaction of 3d-century Christians to the behavior of the so-called libellatici, i.e., those who purchased or secured in some other manner libelli, or certificates attesting that they had conformed to idolatrous religious tests required by an edict of Decius, even though they had not in fact done so.
Idolatry is not formally sinful on the part of those who are in inculpable ignorance of the true God and of the sham and falsity of the idol. It is, however, a misfortune and an evil, because the worshiper puts his trust in a lifeless idol from which no good can come [Ps 113B (115)] and accepts in some degree at least the perversion or distortion of values that it represents.
In modern times idolatry in any strict sense of the word is not a sin of frequent occurrence in the Western world, although it appears to have a place in the practices of devil worship and satanism. For the most part, however, modern man's closest acquaintance with it is likely to be in its metaphorical form, i.e., the idolatry into which one falls when he attributes supreme value to something less than God and pursues it as his ultimate goal in life. Avarice in its grosser forms seems to invite this metaphor. It is the worshiping of a golden calf; thus Our Lord personified Mammon and represented it as a false god (Mt 6.24), and St. Paul spoke of covetousness as a serving of idols (Eph 5.5; Col 3.5).
Bibliography: thomas aquinas, ST 2a2ae, 94, 1–4. a. michel, Dictionnaire de théologie catholique, ed. a. vacant et al. (Paris 1903–50) 7:602–669.
[p. k. meagher]
"Idolatry." New Catholic Encyclopedia. . Encyclopedia.com. (August 14, 2018). http://www.encyclopedia.com/religion/encyclopedias-almanacs-transcripts-and-maps/idolatry-0
"Idolatry." New Catholic Encyclopedia. . Retrieved August 14, 2018 from Encyclopedia.com: http://www.encyclopedia.com/religion/encyclopedias-almanacs-transcripts-and-maps/idolatry-0