As concerning therefore the eating of those things that are offered in sacrifice unto idols, we know that an idol is nothing in the world, and that there is none other God but one. Things that are offered in sacrifice - See on the first verse, (1 Corinthians 8:1 (note)).
An idol is nothing in the world - Dr. Lightfoot translates this, We know that there is no idol in the world; which he explains thus: Ειδωλον, idol, is ὁμοιωμα, εικων, σημειον, χαρακτηριον, σκιοειδες, a likeness, an image, a sign, a character, a shadow: now ουδεν ειδωλον signifies there is no idol, no representation of God, in the world. Images there are of stone, wood and metal; but none of these is any representation of the infinite Spirit. But I prefer the meaning given in the note on 1 Corinthians 8:1; (1 Corinthians 8:1 (note)) as the expression, an idol is nothing in the world, was common in the Old Testament, and among the Jews; and was understood by them in this way: they are not אלהים Elohim, the true God; but they are אלילים, nothings, and הבלים habalim, Vanity.