3-john 1:11

Follow not that which is evil - Μμ μιμου το κακον· Do not imitate that wicked man, i.e., the conduct of Diotrephes; be merciful, loving, and kind. For whatever profession any man may make, it will ever appear that he who doeth good is of God - he alone is the person who uses rightly the grace received from God, and he alone shall enjoy the Divine approbation;

While he that doeth evil - He who is unfeeling, unmerciful, unkind, hath not seen God - has no proper knowledge of that God whose Name is mercy, and whose Nature is love.

Beloved, follow not that which is evil, but that which is good - There can be no doubt that in this exhortation the writer had Diotrephes particularly in his eye, and that he means to exhort Gaius not to imitate his example. He was a man of influence in the church, and though Gaius had shown that he was disposed to act in an independent manner, yet it was not improper to exhort him not to be influenced by the example of any one who did wrong. John wished to excite him to acts of liberal and generous hospitality.

He that doeth good is of God - He shows that he resembles God, for God continually does good. See the sentiment explained in the notes at 1 John 3:7.

He that doeth evil hath not seen God - See the notes at 1 John 3:8-10.

1:11 Follow not that which is evil - In Diotrephes.But that which is good - In Demetrius.He hath not seen God - Is a stranger to him.