2 John 1:10

1:10 If anyone comes to you and does not bring this teaching, do not receive him into your house and do not give him any greeting, ¹ 

[1:10]  ¹ sn Do not give him any greeting does not mean to insult the person. It means “do not greet the person as a fellow Christian” (which is impossible anyway since the opponents are not genuine believers in the author’s opinion).