The Catechism of the Catholic Church teaches:
I expressed what the Catechism teaches in a paper of mine from Nov. 1996:
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
42 Ps 115:4-5, 8; cf. Isa 44:9-20; Jer 10:1-16; Dan 14:1-30; Bar 6; Wis 13:1-15:19.
43 Josh 3:10; Ps 42:3; etc.
44 Mt 6:24.
45 Cf. Rev 13-14.
46 Cf. Gal 5:20; Eph 5:5.
47 Origen, Contra Celsum 2,40:PG 11,861.
To be an idolater is fundamentally to put something in place of God. An animist who is truly worshiping a statue of wood or stone or amulet as God in and of itself (i.e., over against the true, one Creator God) is a true idolater.
I made a similar point in a recent exchange on images used in conjunction with worship (re-edited a bit presently):
I would contend that very few people are so stupid as to think that a wooden crucifix or plaster statue of Christ is Christ Himself, and to be worshiped. They are simply devotional aids, to help concentrate one’s mind on God, just as virtually all Christians would accept painted portraits of Jesus as pious items that help us reflect on our wonderful Lord and Savior and what He has done for us, making it possible to be saved from our sins and go to heaven one day.
In the case of statues of saints, they help us honor or venerate them, which is a separate discussion. So this criticism would apply to so few people as to be miniscule and virtually an irrelevant concern: one in a thousand profoundly ignorant and nominal Catholics, if even that many.
Photo credit: Kleon3 (5-27-18). Participants in a historic religious procession during the 2018 Heiligdomsvaart (Relics Pilgrimage) in Maastricht, Netherlands. This is a statue of the venerated “Madonna and Child, Cause of our Joy”, from Tongeren, Belgium. [Wikimedia Commons / Creative Commons Attribution-Share Alike 4.0 International license]