The elder to the elect lady and her children, whom I love in truth; and not I only, but also all they that know the truth. 2 For the truth's sake which abides in us, and shall be with us for ever. 3 Grace, mercy, peace shall be with us, from God the Father and from Jesus Christ, the Son of the Father, in truth and love.
4 I rejoice greatly that I have found some of your children walking in truth, even as we received commandment from the Father. 5 And now lady, I urge you not as though I write a new commandment, but that which we had from the beginning, that we love one another. 6 And this is love, that we should walk after His commandments. This is the commandment, even as you heard from the beginning, that you should walk in it.
7 For many deceivers have gone out into the world, especially those that do not confess that Jesus Christ came in the flesh. This is the deceiver and the antichrist. 8 Look to yourselves, that we do not lose the things which we have done but that we receive a full reward.
9 Whoever goes ahead and does not continue in the teaching of Christ, does not have God. He that continues in the teaching, the same has both the Father and the Son. 10 If anyone comes to you and does not bring this teaching, do not welcome him into your house and give him no greeting. 11 For he that gives him greeting partakes in his evil works.
12 Having many things to write to you, I would not write them with paper and ink; but I hope to come to you and to speak face to face, that your joy may be made full. 13 The children of your elect sister salute you.
:6 Love isn’t the passing emotion which the world calls love. Love for God and each other involves keeping His commandments; it’s not enough to just be vaguely attracted to the ethos of Christianity in a casual manner.
:7 It could be argued that those who believe in the Trinity have denied that Jesus was in the flesh. Whilst we can leave all judgment to God, the question of the nature of Jesus is therefore crucial- because according to our understanding of Him, so will we live our lives.
:10 The early preachers travelled from home to home, and were supported by Christian families who welcomed them into their homes (3 Jn. 6). John is saying that missionaries who don’t teach the right thing about Jesus shouldn’t be given this support.