John Calvin Commentary 1 Corinthians 8:4

"Concerning therefore the eating of things sacrificed to idols, we know that no idol is [anything] in the world, and that there is no God but one." — 1 Corinthians 8:4 (ASV)

Concerning, therefore, the eating of those things: He now returns to the statement with which he had begun and speaks more plainly regarding the pretext used by the Corinthians. For as the whole of the evil arose from this root — that they were pleased with themselves and despised others — he condemns, in general, that contemptuous knowledge which is not seasoned with love.

Now, however, he explains particularly the kind of knowledge on which they prided themselves: that an idol is an empty figment of the human brain and must therefore be considered as nothing. Accordingly, the consecration performed in the name of the idol is a foolish imagination and of no importance, and a Christian, therefore, is not polluted who, without reverence for the idol, eats of things offered to idols. This is the sum of their excuse, and Paul does not set it aside as false (for it contains excellent doctrine), but because they abused it, in opposition to love.

Regarding the words, Erasmus reads this way: “An idol has no existence.” I prefer the rendering of the old translation: “An idol is nothing.” For the argument is this: an idol is nothing, because there is but one God. For it follows admirably: “If there is no other God besides our God, then an idol is an empty dream, and mere vanity.” When he says, and there is no other God but one, I understand the conjunction “and” as meaning “because.”

For the reason an idol is nothing is that it must be evaluated according to the thing it represents. Now it is appointed for the purpose of representing God; furthermore, for the purpose of representing false gods, because there is but one God, who is invisible and incomprehensible.

The reason, too, must be carefully observed: An idol is nothing because there is no God but one; for He is the invisible God and cannot be represented by a visible sign so as to be worshipped through it. Whether, therefore, idols are erected to represent the true God or false gods, it is in all cases a perverse contrivance.

Hence Habakkuk calls idols teachers of lies (Habakkuk 2:18), because they deal falsely in pretending to give a figure or image of God, and deceive people under a false title. Hence οὐδεν (nothing) refers not to essence, but to quality — for an idol is made of some substance, either silver, or wood, or stone; but as God does not choose to be represented in this way, it is vanity and nothing in terms of meaning and use.