It seems that the knowledge
that is emphasized by the Corinthians is that which we find in Deuteronomy 6:4. It is the knowledge that the Lord God is the only God. Consequently, an idol has no real existence
(perhaps, although it cannot be said for certain, this statement was used as a confessional formula in the churches of Paul’s time).
Evidently, it is not the content of the Corinthians’ knowledge that is problematic. The belief that there is only one God is central to biblical faith, and central to loving God (Deuteronomy 6:4–5). Yet the Corinthians’ application of this belief is problematic. It is possible to know the truth and yet to apply one’s knowledge in a loveless manner.
4 Therefore, as to the eating of food offered to idols, we know that “an idol has no real existence,” and that “there is no God but one.”