3 John 1:12Meaning & Commentary from the Church Fathers

He praises Demetrius, who acts in the same way as Gaius, and gives faithful testimony concerning his virtue. “By all” means by those who possess the truth. “By the truth itself” means in word and deed. For even though some testify concerning another’s virtue, the testimony proves false when reality does not correspond to the words. But if, because of the breadth of the word “all,” someone understands it to mean both believers and unbelievers, his understanding is not unjust. For the Apostle Paul commands all the faithful: “Give no offense either to Jews or to Greeks or to the Church of God, just as I also please all men in all things” (1 Cor 10:32-33).

As testimony is offered concerning him, so it is acknowledged because of his virtue. Others, however, wish to interpret this testimony in a bad sense, because it does not seem especially favorable to them.

As I suppose, Demetrius is the maker of silver shrines of Artemis who once stirred up a riot against the Apostle Paul. See Acts 19:24-38.

We know absolutely nothing about this Demetrius, who merited such praise from the Apostle and testimony from the truth itself, that is, from God, for his virtues. Yet he was certainly very well known to the Church to which Gaius belonged.

Concerning Demetrius and the rest, it is not precisely known who this Demetrius was, whom the Apostle praises so highly. There is a tradition, recorded by Dorotheus of Tyre, that he later became bishop of Philadelphia, one of the cities mentioned in the Apocalypse (Rev 3:7 and following). “He has been testified to by all,” and so forth. The Apostle points to several witnesses concerning Demetrius. All testify, the truth itself testifies, and the Apostle himself testifies. “By all” means by the whole Church, or by all the Churches that know of him [...]. “By the truth itself” means that his own works testify to the truth that he walks in truth. Compare the note on 2 Jn 4. “And we” means the Apostle personally. Compare the notes on Jn 19:35 and Jn 21:24.

Demetrius is probably mentioned because the Epistle was sent with him. Therefore, wishing him to be received according to his dignity, the Apostle points to his special merits, and perhaps even to miracles. In these the testimony of the Spirit of truth concerning him was manifested. John joins to this his own testimony, strengthened by the customary indication of its trustworthiness. Compare Jn 21:24.