2 John Chapter 1

4 I rejoiced greatly to find some of your children walking in the truth, just as the Father commanded us.
5 And now I urge you, dear lady, not as though I were writing you a new commandment, but the one we have had from the beginning: that we love one another.
6 And this is love, that we walk according to his commandments. This is the commandment: that you walk in love, just as you have heard from the beginning.
7 For many deceivers have gone out into the world, those who do not confess that Jesus Christ has come in the flesh. Such a person is the deceiver and the antichrist.
8 Watch yourselves, so that you may not lose what you have worked for, but may receive a full reward.
9 Anyone who runs ahead and does not continue in the teaching of Christ does not have God; whoever continues in the 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 or even greet him.
11 For whoever greets him shares in his wicked works.