Paul begins with the topic of food sacrificed to idols. He acknowledges that all have knowledge, but knowledge puffs up while love builds up. Anyone who thinks he knows something does not yet know as he ought; but anyone who loves God is known by him.
On eating food sacrificed to idols, Paul affirms that an idol is nothing in the world and that there is no God but one. Even if there are many so-called gods and lords, for us there is one God, the Father, from whom are all things, and one Lord, Jesus Christ, through whom are all things and through whom we exist.
But not everyone has this knowledge. Some, accustomed until now to idols, eat the food as something sacrificed to an idol, and their weak conscience is defiled. Food does not bring us closer to God: we are no worse if we do not eat and no better if we do. Paul warns that their freedom must not become a stumbling block to the weak. If someone with knowledge is seen eating in an idol's temple, a weak brother might be emboldened to eat against his conscience, and so the one for whom Christ died is destroyed. Sinning against brothers by wounding their weak conscience is sinning against Christ. So Paul concludes that if food makes his brother fall, he will never eat meat, so that he will not make him stumble.