2 John 1:5-11 - Warning Against False Teachers
5 But now I ask you, lady (not as if I were writing a new commandment to you, but the one we have had from the beginning), that we love one another. 6 (Now this is love: that we walk according to his commandments.) This is the commandment, just as you have heard from the beginning; thus you should walk in it.
7 For many deceivers have gone out into the world, people who do not confess Jesus as Christ coming in the flesh. This person is the deceiver and the antichrist! 8 Watch out, so that you do not lose the things we have worked for, but receive a full reward. 9 Everyone who goes on ahead and does not remain in the teaching of Christ does not have God. The one who remains in this teaching has both the Father and the Son. 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, 11 because the person who gives him a greeting shares in his evil deeds.