I am in the Lord Jesus, and I know that there is no food that is wrong to eat. But if a person believes something is wrong, that thing is wrong for him.
But those who eat something without being sure it is right are wrong because they did not believe it was right. Anything that is done without believing it is right is a sin.
But not all people know this. Some people are still so used to idols that when they eat meat, they still think of it as being sacrificed to an idol. Because their conscience is weak, when they eat it, they feel guilty.