2 John 1:1
1 The elder unto the elect lady and her children, whom I love in the truth; and not I only, but also all they that have known the truth;
This letter to the "elect lady" is principally concerned with the Truth, the word being constantly repeated. The apostle wrote with conviction of the importance of Truth in its effect on life. In declaring his joy that the children of the elect lady were walking in Truth, he wrote the central commandment, "that we love one another." Love is obedience to light, that is, to Truth. It is of the utmost importance that love should be of the true nature. Any consent to darkness out of a so-called charity is not love. Loyalty to the Lord is the true way of love, and anything which compromises that is false, and eventually violates love.
The reason for the letter is discovered in the words, "deceivers are gone forth." The heresy of these teachers was the denial of the Incarnation, "Jesus Christ coming in the flesh." The apostle referred to supposedly progressive teaching. There were those who were "going on." Progress which denies fundamental Truth is retrogression. All development which is destruction is disastrous. So important is this that the apostle urged that no hospitality or greeting is to be given to those who by false teaching imperil the life and light and love of the believer.
The teaching of the letter may thus be summarized. Christianity is love. Love is dependent on the light of Truth. To deny the Truth is to make love impossible. The continued experience of fellowship is dependent on the continued fact of fellowship in love and light and life. The continued fact of fellowship is proved by the continued experience of fellowship.