3 John 1:11
11 Beloved, follow not that which is evil, but that which is good. He that doeth good is of God: but he that doeth evil hath not seen God.
The Grace New Testament Commentary - 3 John 1:11
1:11 Gaius is not to imitate what is evil. If he did, then it could be said of him that he had not seen God! Conversely, if he did the right thing, it could be said that he was of God. To be of God signifies that the action of the person in question has its source in God (cf. 1 John 3:10). Sin, on the other hand, is always an act performed in spiritual ignorance and darkness. The sinner acts sinfully because he has lost sight of God (cf. 1 John 3:6).
The Greek articular present participle is used in the phrases He who does good (ho agathopoiōn) and he who does evil (ho kakopoiōn), but these expressions imply no more than that the action is performed. Such participles can express actions that occur only once (e.g., John 6:33, ho katabainōn, "He who comes down") or actions that are no longer occurring (e.g., John 9:8, ho kathēmenos kai prosaitōn, "he who sat and begged"). The statements remain true whether good or evil is done once or many times.
Gaius therefore is being told that if he does good by receiving Demetrius (v 12), in so doing he will be of God. That is, he will be behaving in such a way that God Himself is the source of what he is doing. Alternatively if he imitates Diotrephes and does evil, he will be acting out of spiritual blindness and will have had no perception of God.
Charles Bing - Grace, Salvation, and Discipleship - Whoever Does Evil Has Not Seen God, 3 John 1:11
(Salvation) Interpretation: Those who do evil are not saved.
(Discipleship) Interpretation: Believers who do evil evidence a lack of an intimate knowledge of God.
The key to interpreting this passage is the meaning of the phrase "has not seen God." Does it refer to someone who is not saved eternally, or someone who is saved but blind to the true character of God? It would have helped us if John had used the familiar first person plural "we" that he often uses in his epistles - we could conclude that he is addressing the experience of Christians who do not "see" the true character of God. But John uses the second person "he." This makes sense in the context because John had just mentioned Diotrephes, who is acting badly (vv. 9-10), and next mentions Demetrius, who is doing good (v. 12).
John exhorts the "beloved" Christian Gaius, probably the leader of the church in Ephesus, to imitate those like Demetrius, not those like Diotrephes. Certainly, as a Christian, it is possible for Gaius to make either choice. John's exhortation is based on the fact that the one who does good is of God and the one who does evil has not seen God. As we have seen in 1 John, to be "of God" is to show that God is the source of inspiration of one's action (1 John 3:10). On the other hand, someone who "has not seen God" is walking in darkness (1 John 1:6) and is acting in spiritual blindness. All sin originates from losing sight of God (1 John 3:9). The idea of seeing God refers to one's perception and experience of something (cf. Luke 3:6; John 6:36; 12:45; 14:9; 15:24; and see the discussion of Heb. 12:14), so not seeing God is a clouded perception, a lack of an intimate knowledge of God.
Some may argue that the present participles ("He who does good/he who does evil") suggest continuous or habitual action. But as we have seen in 1 John 3:6, 9, this is stretching the use of the present beyond its intention, which is to simply state an action (cf. John 6:33).
The important (Discipleship truth) that we take from this passage is that if we take our eyes off God, we too can do evil and show a lack of familiarity with God's character and nature. When we do good however, we show that God is the source of our action. Like Gaius, we should avoid behaving like those who are spiritually blind and imitate those who show an intimate knowledge of God.