Titus 3:10 & 11
Warn a divisive person once, and then warn him a second time. After that, have nothing to do with him. You may be sure that such a man is warped and sinful; he is self-condemned.
These are strong words but Paul uses them because of the fact that he knows how dangerous legalism is to the faith. When he says "divisive person" he is talking about someone who wants to argue about a certain point of the law. What he is saying is that, if we remember that we are under grace and not the law, then the finer points of religious law are not important to us. If they are that important to someone else, then that person is putting their trust in obedience to the law and not the grace of God. If that is where they are putting their trust, then they are already condemned by their own heart and there is no need for us to argue with them. Our job is not to save people but to tell them the truth and so we can tell them where they are wrong in their thinking and our job is done.