1:12 Demetrius 3 has been testified to by all, even by the truth itself. We also testify to him, 4 and you know that our testimony is true.
1 sn The exhortation do not imitate what is bad but what is good is clearly a reference to Diotrephes’ evil behavior. The author exhorts Gaius (whom he wishes to continue assisting the missionaries) not to follow the negative example of Diotrephes, but to do what is right. Implicitly there may be a contrast between the bad behavior of Diotrephes and the good reputation of Demetrius (mentioned in the following verse); but it seems more likely that Demetrius is himself one of the traveling missionaries (perhaps their leader), rather than the leader of a local congregation who, unlike Diotrephes, has supported the missionaries himself.
2 sn The statement The one who does what is bad has not seen God is asyndetic; its abrupt introduction adds emphasis. The statement reiterates the common Johannine theme of behavior as an indication of genuine faith, found in 1 John in 3:6, 10; 4:7, 20; and in the Gospel of John in 3:17-21. By implication, the genuineness of Diotrephes’ faith is called into question, because he has obviously done what is bad (v. 11b; cf. vv. 9-10). In John’s terminology it is clear that the phrase has not seen God is equivalent to “is not a genuine Christian” (see John 3:17-21 and 1 John 3:6, 10; 4:7, 20).
3 sn Demetrius is apparently someone Gaius would have heard about, but whose character was not known to him. Thus the author is writing to Gaius to attest to Demetrius’ good character. It appears that Demetrius is coming to Gaius’ church and needs hospitality and assistance, so the author is writing to commend him to Gaius and vouch for him. It is difficult to know more about Demetrius with any certainty, but the author is willing to give him a powerful personal endorsement (We testify to him too). Demetrius may well have been the leader of a delegation of traveling missionaries, and may even have been the bearer of this letter to Gaius. The writing of letters of introduction to be carried along by representatives or missionaries in NT times is also attested in Paul’s writings (1 Cor 16:3).
4 tn The words “to him” are not in the Greek text, but are implied.