I rejoiced greatly that I have found some of your children walking in truth, as we received commandment from the Father. And now I plead with you, lady, not as though I wrote a new commandment to you, but that which we have had from the beginning: that we love one another. This is love, that we walk according to His commandments. This is the commandment, that as you have heard from the beginning, you should walk in it.
For many deceivers have gone out into the world who do not confess Jesus Christ as coming in the flesh. This is a deceiver and an antichrist. Look to yourselves, that we do not lose those things we worked for, but that we may receive a full reward.
Whoever transgresses and does not abide in the doctrine of Christ does not have God. He who abides in the doctrine of Christ has both the Father and the Son. If anyone comes to you and does not bring this doctrine, do not receive him into your house nor greet him; for he who greets him shares in his evil deeds.
2 John 4-11 NKJV