It's the Law!

The story of Cornelius and Peter in chapter 10 of the Acts of the Apostles is a valuable look at attitudes toward the Law.  Until this incident no Gentile (non-Jew) had been received into the community of Christ's followers.  The Jewish Law even forbade Jews to enter the homes of Gentiles.
Peter has a vision telling him to eat animals that the Law said was unclean.  God says to him, "What God has made clean you must not call profane."
So when Cornelius, a Gentile, asks Peter to come to his "un-clean" house, Peter understands that he must go despite the Law.  Peter receives Cornelius and his household into the community of Christ's followers.  He knows that he will be criticized by his fellow Christians, all of whom were still obeying the Jewish Law.
"When is it wrong to obey the law?" is not a new question for Christians.