So if I come, I will bring up what he is doing, prating against me with evil words. And not content with that, he refuses himself to welcome the brethren, and also stops those who want to welcome them and puts them out of the church.
διὰ τοῦτο, ἐὰν ἔλθω, ὑπομνήσω αὐτοῦ τὰ ἔργα ἃ ποιεῖ λόγοις πονηροῖς φλυαρῶν ἡμᾶς, καὶ μὴ ἀρκούμενος ἐπὶ τούτοις οὔτε αὐτὸς ἐπιδέχεται τοὺς ἀδελφοὺς καὶ τοὺς βουλομένους κωλύει καὶ ἐκ τῆς ἐκκλησίας ἐκβάλλει.
Haydock Catholic Bible Commentary: 3 John
Diotrephes . . . doth not receive us, nor those we recommend, but prattles and talks against me. We know no more of this man, nor of Demetrius, of whom S. John gives so favourable a character. Wi. — It seemeth, saith Ven. Bede, that he was an arch heretic, or proud sect master—upomnhsw. I will rebuke them, and make them known to be wicked. Bede.