Expositor's Bible Commentary Commentary 1 Corinthians 8:7

"Howbeit there is not in all men that knowledge: but some, being used until now to the idol, eat as [of] a thing sacrificed to an idol; and their conscience being weak is defiled." — 1 Corinthians 8:7 (ASV)

The knowledge Paul speaks of here is the previously mentioned knowledge regarding an idol and the existence and position of the “so-called gods.” Some may not fully realize the significance of these truths, because in their former unsaved state they had become so accustomed to idols and to the sacrificed meat that when they now eat such meat, they think of it only as something sacrificed to the idol, rather than as food provided by God. Their moral awareness—their conscience—is weak, being unable to discriminate in these matters, and so is defiled.