‘Beloved, do not imitate what is evil, but what is good. He who does good is of God. He who does evil has not seen God.'
Meanwhile Gaius is to continue in goodness. As with all true Christians he must take his example from Christ, imitating what is good and not what is evil. For being a Christian, and doing good, go together. Those who do good are of God. But those who do evil have not seen God. They cannot have, for God is light, and had they seen Him they would have repented. John is quite clear. You will know men by their fruits. He knew nothing of a salvation that did not produce fruit.