Charles Spurgeon Commentary 1 John 3:16-19

"Hereby know we love, because he laid down his life for us: and we ought to lay down our lives for the brethren. But whoso hath the world`s goods, and beholdeth his brother in need, and shutteth up his compassion from him, how doth the love of God abide in him? [My] Little children, let us not love in word, neither with the tongue; but in deed and truth. Hereby shall we know that we are of the truth, and shall assure our heart before him:" — 1 John 3:16-19 (ASV)

Because he laid down his life for us: and we ought to lay down our lives for the brethren. But whoso hath this world's good, and seeth his brother have need, and shutteth up his bowels of compassion from him, how dwelleth the love of God in him? My little children, let us not love in word, neither in tongue, but in deed and in truth. And hereby we know that we are of the truth, and shall assure our hearts before him.

That is still the test; truthful love proves that we are of the truth, children of the God of truth, and so assures and tranquillizes our hearts before him.

Our hearts shall be calm, confident, and happy before God, when we know that true love flows within them.