Commentaries
1:9-12 Both the heart and mouth must be watched. The temper and spirit of Diotrephes was full of pride and ambition. It is bad not to do good ourselves; but it is worse to hinder those who would do good. Those cautions and counsels are most likely to be accepted, which are seasoned with love. Follow that which is good, for he that doeth good, as delighting therein, is born of God. Evil-workers vainly pretend or boast acquaintance with God. Let us not follow that which is proud, selfish, and of bad design, though the example may be given by persons of rank and power; but let us be followers of God, and walk in love, after the example of our Lord.
11. follow not that which is evil—as manifested in Diotrephes (3Jo 9, 10).
but … good—as manifested in Demetrius (3Jo 12).
is of God—is born of God, who is good.
hath not seen God—spiritually, not literally.