Hereby shall we know that we are of the truth, and shall assure our heart before him:
Verse 19. And hereby. Gr., by this; that is, by the fact that we have true love to others, and that we manifest it by a readiness to make sacrifices to do them good. We know that we are of the truth. That we are not deceived in what we profess to be; that is that we are true Christians.
And hereby we know that we are of the truth, and shall assure our hearts before him. (19) He commends charity, by three effects: for first of all, by it we know that we are indeed the sons of God, as he showed before.
19 And hereby we know, or, by this we know. The word truth, he takes now in a different sense; but there is a striking similarity in the words, — If we, in truth, love our neighbors, we have an evidence that we are born of God, who is truth, or that the truth of God dwells in us.