1-john 2:3

And hereby we do know that we know him - If we keep the commandments of God, loving him with all our heart, and our neighbor as ourselves, we have the fullest proof that we have the true saving knowledge of God and his Christ. The Gnostics pretended to much knowledge, but their knowledge left them in possession of all their bad passions and unholy habits; they, therefore, gave no proof that they had known either God or his Son Jesus - nor is any man properly acquainted with God, who is still under the power of his sins.

And hereby we do know that we know him - To wit, by that which follows, we have evidence that we are truly acquainted with him, and with the requirements of his religion; that is, that we are truly his friends. The word "him" in this verse, seems to refer to the Saviour. On the meaning of the word "know," see the notes at John 17:3. The apostle had stated in the previous part of this Epistle some of the leading points revealed by the Christian religion, and he here enters on the consideration of the nature of the evidence required to show that we are personally interested in it, or that we are true Christians. A large part of the Epistle is occupied with this subject. The first, the grand evidence - that without which all others would be vain - he says is, that we keep his commandments.

If we keep his commandments - See the notes at John 14:15. Compare John 14:23-24; John 15:10, John 15:14.

2:3 And hereby we know that we truly and savingly know him - As he is the advocate, the righteous, the propitiation. If wekeep his commandments - Particularly those of faith and love.