21 PTE: You might eat some meat or drink some wine or things like that, you know it is alright, it is not wrong for you to do like that. Another person might see you do like that, he might think it is wrong to do like that, he might want to do like that, he might do like that just because he saw you do it. While ever he thinks it is wrong to do that, it is indeed wrong for him. God would punish him for doing it.
Lest that happen to him, you should always do the right thing, you should leave doing things that make trouble for other people. Perhaps they are good things, that other person thinks they are bad. You should leave them. Then that other person will not do what he thinks is a bad thing, he will not get into trouble because of you.