I have written something to the church, or ‘I have written (or sent) a letter to the church,’ or simply ‘I have written to the church.’ The Greek verb is in the aorist and shows that the reference is to specific fact in the past. The writing thus referred to is not identical with what is called the Second Letter of John. For the verb compare comments on 1 John 1.4.
The church presumably refers here to the congregation Gaius belongs to. Accordingly some versions specify ‘your church/congregation,’ ‘the people of Christ who are with you (or at your place).’
The elder fears that the letter referred to will not accomplish anything. The reason for this is stated in the next clause: Diotrephes … does not acknowledge my authority (literally “does not receive/accept us”). This first person plural pronoun “us” may stand for the singular in letter writing; compare 2 John 12. But the plural may also be taken as referring to the elder and his followers in the congregation from which he is writing. In the latter case it has exclusive force. The same is true of “me” in verse 10, and “I” and “my” in verse 12. The singular seems to be the slightly more probable interpretation.
The Greek verb usually means “to receive as a guest” (for example, in verse 10), but here it probably has the sense of “to accept what a person says” (Goodspeed). This leads to renderings like ‘Diotrephes … does not respect me,’ ‘Diotrephes … will have nothing to do with me’ (compare New English Bible), “Diotrephes … will not pay any attention to what I say” (Good News Translation).
Nothing is known about Diothrephes except what is told here. He appears to have been an influential and tyrannical man who tried to isolate the congregation he wanted to control. Nothing shows that he held an office in the congregation.
Who likes to put himself first, or “who loves to be their leader” (Good News Translation), ‘who likes to boss them’ (or ‘you,’ when the second person has been specified in what precedes), ‘who wants to make himself greater than all others.’ This relative clause indicates the reason why Diotrephes is behaving like this. To bring this out some versions shift to a rendering like ‘because he pretends to be their chief.’
Quoted with permission from Haas, C., de Jonge, M. and Swellengrebel, J.L. A Handbook on The Third Letter of John. (UBS Handbook Series). New York: UBS, 1972. For this and other handbooks for translators see here .