If I come (or ‘when I come,’ ‘at the time I come’) refers to something that is viewed as an event that will certainly happen; compare comments on “when” in 1 John 2.28.

In I will bring up, the Greek verb means “to remind,” “to call to mind.” It often implies warning or blame, as it does here and in 2 Tim 2.14; hence ‘to expose,’ ‘to bring to light.’

The expression what he is doing, or ‘his behavior,’ is neutral in itself, but the four items mentioned in the following explanation show his behavior to be bad.

Prating against me with evil words is the first item. The clause may be better rendered as a new sentence, ‘He is prating….’

The verb used has the meaning ‘to talk nonsense about,’ ‘to gossip,’ ‘to speak idly/irresponsibly.’ The qualifying phrase with evil words serves to emphasize the unfavorable meaning of the verb. The whole phrase expresses the hostility Diotrephes has shown to the elder. Accordingly the phrase expresses the concept “to slander,” that is, “to damage a person’s reputation by false charges.” Some renderings used are ‘he continually speaks badly/ill of me,’ ‘he spreads slanderous gossip about me,’ ‘telling stories and lies about me,’ ‘talking just-behind me hatefully,’ ‘he always brings to the fore my name.’

Three further bad items are added to the first one by means of the phrase and not content with that, or “not satisfied with that” (New English Bible), or, as a new sentence, “But that is not enough for him” (Good News Translation), ‘He doesn’t stop at that,’ ‘That is not the end of it,’ ‘That is not the only thing he does.’

He refuses himself to welcome the brethren, or ‘he himself does not receive the brothers at his town (or congregation),’ ‘he himself does not show hospitality to the brothers’—this is the second item. The present tense expresses custom. The brethren refers to the traveling preachers who come to visit the congregation.

He … also stops those who want to welcome them is the third item. The Greek literally has “stops those who want,” which is elliptical. As a rule such words as “to welcome them” have to be added in order to fill up the ellipsis. The tense of the first verb may express attempt; hence ‘tries to stop.’ The same holds true of ‘puts them out’ in the next clause.

The main verb, stops, means “to keep from doing (by deeds or words),” “to hinder,” “to forbid.” Some renderings of the clause are “he is interfering with those who want to do so” (Goodspeed), ‘he closes the way for people who want to welcome them,’ ‘to people who want to welcome them he says, “Do not do so,” ’ ‘he tells others not to do so.’ “Them” refers back to “the brethren.”

He … puts them out of the church is the fourth and last item. “To put out” means “to drive out,” “to expel,” more or less forcibly. The word may refer to official excommunication from the congregation, but it can also be taken in a less forceful sense. In the latter case it serves to indicate that Diotrephes stirred up the congregation against the persons in question, thus isolating them and curbing their influence.

In this clause them refers to the members of the congregation who want to welcome the visiting preachers, contrary to what Diotrephes wants them to do. One may have to make this explicit, for example, by using ‘such people,’ or ‘every one who does so’ as substitute for them.

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 .