“Beloved, do not imitate what is evil, but what is good. The one who does good is of God; the one who does evil has not seen God.” (III John 11)
Here John encourages his readers to imitate those who do good. It is instructive that this exhortation follows his description of Diotrephes, “who loves to be first among them” (:9) and who made false accusations against John and the other apostles, and did not support the traveling evangelists (:10). THEN, immediately following his exhortation to imitate what is good, John commends Demetrius in :12, whom he says “has received a good testimony from everyone.”
So John sets forth these two men as examples to his readers: one an example of what is good, and the other of what is NOT. Basically he’s saying to them: Imitate Demetrius, not Diotrephes.
We should learn from this, first of all to avoid the pride and evil tendencies that marked Diotrephes. But it should also cause each of us to search our own lives: what kind of example am I? What would John, if he were writing to the people in my church, have to say about the example of MY life? Would he say that I maintained a good testimony, and that I am worthy of imitation by them? Or would he have to say of me — or of some particular area of my life — “do not imitate what is evil”? In your church, are you a Diotrephes, or a Demetrius?