In these passages, Paul again speaks of how our actions affect others. We are to be sensitive to this. In Paul’s day believers who were not yet strong or mature in the Faith believed that eating meat which had been offered to a demon or idols was a sin. Some meat that was sold in the marketplace had been previously offered to demons. It was not a sin to eat such meat. However, if one believed it was a sin and ate the meat, then to them it was indeed a sin. They were violating their convictions and doing what they believed was wrong.
Paul said that strong believers must be aware of this. They should avoid eating such meat, if it influences the weak believer to do what they believe is wrong.
Though we may be free to do certain things, we must be sensitive to the beliefs of others. The Bible says that we are to love others as ourselves. So, we must always seek what is best for others and not be concerned only for ourselves.