The knowledge of which Paul speaks is the understanding that idols are nothing; therefore, food that is offered to them is perfectly acceptable fare for one’s table. Unless, Paul explains, another brother in Christ does not have this knowledge. Then your knowledge that it is acceptable and “this right of yours [to eat food offered to idols] becomes a stumbling block to the weak.” (1 Corinthians 8:9) And, at this point, if you allow your knowledge to harm your brother, you are no longer acting in love.
Paul says, “Love builds up.” He warns, “Now when you sin like this against the brothers and wound their weak consciences, you are sinning against Christ.” (1 Corinthians 8:12) If that which I know to be acceptable, nevertheless harms my brother in Christ, “I will never again” do that. “so that I won’t cause my brother to fall.” (1 Corinthians 8:13)
Paul writes to the church at Corinth, “If anyone thinks he knows anything, he does not yet know as he ought to know it. But if anyone loves God, he is known by Him.”