Summa Theologica

...To the fourth, it must be said that the heresy of the Manichaeans is more grievous, even as to the genus of the sin, than the sin of other idolaters, because they derogate more from divine honor, positing two contrary gods, and feigning many vain and fabulous things about God. It is otherwise, however, with other heretics, who confess one God and worship Him alone.

To the fifth, it must be said that the observance of the Law in the time of grace is not entirely equal to idolatry in the genus of the sin, but almost equal: because both are species of a pestiferous superstition.

ARTICLE IV. — WHETHER THE CAUSE OF IDOLATRY WAS ON THE PART OF MAN.

To the fourth it is proceeded thus. 1. It seems that the cause of idolatry was not on the part of man. For in man there is nothing except nature, or virtue, or guilt. But the cause of idolatry could not be on the part of the nature of man; because the natural reason of man rather dictates that there is one God, that divine cult is not to be exhibited to the dead, nor to inanimate things. Similarly, neither does idolatry have a cause in man on the part of virtue, because a good tree cannot bring forth evil fruit, as is said (Matth. VII, 18). Nor yet on the part of guilt, because, as is said (Wisd. XIV, 27), the worship of idols not to be named is the cause, and the beginning, and the end of all evil. Therefore, idolatry does not have a cause on the part of man.

2. Furthermore, those things which are caused on the part of man are found in men at all times. But idolatry was not always, but is read to have been invented in the second age, either by Nimrod, who, as it is said, compelled men to worship fire; or by Ninus, who caused the image of his father Belus to be worshipped; among the Greeks, however, as Isidore reports (Etymol. lib. VIII, cap. 11, somewhat from the beginning), Prometheus was the first who fashioned images of men out of clay; the Jews, however, say that Ishmael was the first to make a likeness out of clay: idolatry also ceased for the most part in the sixth age. Therefore, idolatry did not have a cause on the part of man.

3. Furthermore, Augustine says (De civit. Dei, lib. XXI, cap. 6, from the middle): “Nor could it be learned at first except by them (namely the demons) teaching what each of them desires, what he abhors, by what name he is invited or compelled; whence the magic arts and their artificers arose.” But the same reason seems to be of idolatry. Therefore, the cause of idolatry is not on the part of men.