Bible Verses About Heresy: Propagandism of, forbidden under severe penalties

Warn a divisive person once, then a second time; and after that, have nothing more to do with him.

You may be sure that such a person has been perverted and is sinning: he stands self-condemned.

If someone comes to you and does not bring this teaching, don’t welcome him into your home. Don’t even say, “Shalom!” to him;

for the person who says, “Shalom!” to him shares in his evil deeds.