Paul is covering this because this is a matter that was decided by the Elders and Apostles in Acts 15. Don't eat meat sacrificed to idols. Now... Paul makes it clear here that we know that an idol is a chunk of wood or stone that is decorated to look like something and in and of itself... it has no life. It's useless. That's his point here but I want to correct another misused passage.
Knowledge makes arrogant but love edifies! I have heard this misused time and time and time again. Paul is FAR from saying knowledge is bad. Knowledge is a must. That isn't Paul's point. Paul is telling us why we are not to eat meat sacrificed to idols... that is the context of this entire discourse. Follow into the next section.
However not all men have this knowledge; but some, being accustomed to the idol until now, eat food as if it were sacrificed to an idol; and their conscience being weak is defiled. But food will not commend us to God; we are neither the worse if we do not eat, nor the better if we do eat. But take care lest this liberty of yours somehow become a stumbling block to the weak. For if someone sees you, who have knowledge, dining in an idol's temple, will not his conscience, if he is weak, be strengthened to eat things sacrificed to idols? For through your knowledge he who is weak is ruined, the brother for whose sake Christ died. And thus, by sinning against the brethren and wounding their conscience when it is weak, you sin against Christ. Therefore, if food causes my brother to stumble, I will never eat meat again, that I might not cause my brother to stumble.
NOT ALL MEN HAVE THIS KNOWLEDGE that idols aren't real. Not all men have the knowledge that there is but one God, the Father, from whom are all things, and we exist for Him; and one Lord, Jesus Christ, by whom are all things and we exist through Him. They are accustomed to the idol and they eat to that idol defiling their weak conscience. This is where knowledge can become arrogant if you are eating meat that was sacrificed to an idol. You know it means nothing for the idol means nothing... but love edifies. I won't eat that meat for the sake of that brother so that I do not encourage him to eat thus defiling his weak conscience causing him to stumble because one I do that.... my sin is against Christ because I ruined a brother for whom Christ died for.
Let's make this practical for today and keep it real with something very controversial among believers today.
Alcoholic beverage: Wine, Beer, Strong Drink.... there are those that say it is a sin to even drink a drop. Some say it is not a sin to drink... just don't get drunk. I say both are right. It is not a sin to drink alcoholic beverage. Listen... the church I belonged to most all of my life preached it a sin to drink. Now... if that is what they believe in their heart then for them to drink it would be a sin. But the foolish notion that the wine, beer, or strong drink they drank in the Bible days wasn't in some way intoxicating... makes folks look stupid. Simple reading of the Scripture makes it rather clear... now and again they'd get looped out of their mind. That's when preachers preach things like Noah sinned thus.... or Lot sinned thus... but then the kick is... the Bible never says that of them in that case. Even getting drunk on rare occasion isn't a sin although when in that state you can find yourself doing something sinful! Being a drunkard is the sin. Having a drink of wine now and again... a beer now and again... or a Margarita at the Mexican restaurant now and again with your taco... it is not a sin. We should have that knowledge.... but beware because that knowledge can turn arrogant. That weaker person... the one that is easily addicted because of a lack of self-control... the one that has had problems in the past... if they stumble because of our knowledge that in moderation this is fine.... we sin against Christ.