The human mind, stuffed as it is with presumptuous rashness, dares to imagine a god suited to its own capacity; as it labours under dullness . . . it substitutes vanity and an empty phantom in the place of God…
The mind, in this way, conceives the idol, and the hand gives it birth. That idolatry has its origin in the idea which men have, that God is not present with them unless his presence is carnally exhibited, appears from the example of the Israelites: “Up,” said they, “make us gods, which shall go before us; for as for this Moses, the man that brought us up out of the land of Egypt, we wet not what is become of him,” (Exod. 22:1).
They knew, indeed, that there was a God whose mighty power they had experienced in so many miracles, but they had no confidence of his being near to them, if they did not with their eyes behold a corporeal symbol of his presence, as an attestation to his actual government. They desired, therefore, to be assured by the image which went before them, that they were journeying under Divine guidance. And daily experience shows, that the flesh is always restless until it has obtained some figment like itself, with which it may vainly solace itself as a representation of God. In consequence of this blind passion men have, almost in all ages since the world began, set up signs on which they imagined that God was visibly depicted to their eyes.
After such a figment is formed, adoration forthwith ensues: for when once men imagined that they beheld God in images, they also worshipped him as being there. At length their eyes and minds becoming wholly engrossed by them, they began to grow more and more brutish, gazing and wondering as if some divinity were actually before them. It hence appears that men do not fall away to the worship of images until they have imbibed some idea of a grosser description: not that they actually believe them to be gods, but that the power of divinity somehow or other resides in them. Therefore, whether it be God or a creature that is imaged, the moment you fall prostrate before it in veneration, you are so far fascinated by superstition. For this reason, the Lord not only forbade the erection of statues to himself, but also the consecration of titles and stones which might be set up for adoration. For the same reason, also, the second commandment has an additional part concerning adoration. For as soon as a visible form is given to God, his power also is supposed to be annexed to it.
So stupid are men, that wherever they figure God, there they fix him, and by necessary consequence proceed to adore him. It makes no difference whether they worship the idol simply, or God in the idol; it is always idolatry when divine honours are paid to an idol, be the colour what it may. And because God wills not to be worshipped superstitiously whatever is bestowed upon idols is so much robbed from him.
Let those attend to this who set about hunting for miserable pretexts in defence of the execrable idolatry in which for many past ages true religion has been buried and sunk. It is said that the images are not accounted gods. Nor were the Jews so utterly thoughtless as not to remember that there was a God whose hand led them out of Egypt before they made the calf. Indeed, Aaron saying, that these were the gods which had brought them out of Egypt, they intimated, in no ambiguous terms, that they wished to retain God, their deliverer, provided they saw him going before them in the calf. Nor are the heathen to be deemed to have been so stupid as not to understand that God was something else than wood and stone.
John Calvin, Institutes of the Christian Religion, I.XI.VIII-IX