1-john 3:24

Dwelleth in him - i.e. in God; and he - God, in him - the believer.

And hereby we know - We know by the Spirit which he hath given us that we dwell in God, and God in us. It was not by conjecture or inference that Christians of old knew they were in the favor of God, it was by the testimony of God's own Spirit in their hearts; and this testimony was not given in a transient manner, but was constant and abiding while they continued under the influence of that faith that worketh by love. Every good man is a temple of the Holy Ghost, and wherever he is, he is both light and power. By his power he works; by his light he makes both himself and his work known. Peace of conscience and joy in the Holy Ghost must proceed from the indwelling of that Holy Spirit; and those who have these blessings must know that they have them, for we cannot have heavenly peace and heavenly joy without knowing that we have them. But this Spirit in the soul of a believer is not only manifest by its effects, but it bears its own witness to its own indwelling. So that a man not only knows that he has this Spirit from the fruits of the Spirit, but he knows that he has it from its own direct witness. It may be said, "How can these things be?" And it may be answered, By the power, light, and mercy of God. But that such things are, the Scriptures uniformly attest, and the experience of the whole genuine Church of Christ, and of every truly converted soul, sufficiently proves. As the wind bloweth where it listeth, and we cannot tell whence it cometh and whither it goeth, so is every one that is born of the Spirit: the thing is certain, and fully known by its effects; but how this testimony is given and confirmed is inexplicable. Every good man feels it, and knows he is of God by the Spirit which God has given him.

And he that keepeth his commandments ... - See the notes at John 14:23.

And hereby we know that he abideth in us - That is, this is another certain evidence that we are true Christians. The Saviour had promised John 14:23 that he would come and take up his abode with his people. John says that we have proof that he does this by the Spirit which he has given us. That is, the Holy Spirit is imparted to his people to enlighten their minds; to elevate their affections; to sustain them in times of trial; to quicken them in the performance of duty; and to imbue them with the temper and spirit of the Lord Jesus. When these effects exist, we may be certain that the Spirit of God is with us; for these are the "fruits" of that Spirit, or these are the effects which he produces in the lives of men. Compare the notes at Galatians 5:22-23. On the evidence of piety here referred to, see the notes at Romans 8:9, Romans 8:14, Romans 8:16. No man can be a true Christian in whom that Spirit does not constantly dwell, or to whom he is not "given." And yet no one can determine that the Spirit dwells in him, except by the "effects" produced in his heart and life. In the following chapter, the apostle pursues the subject suggested here, and shows that we should examine ourselves closely, to see whether the "Spirit" to which we trust, as furnishing evidence of piety, is truly the Spirit of God, or is a spirit of delusion.

3:24 And he that keepeth his commandments - That thus believes and loves. Abideth in him, and God in him: and hereby we know that he abideth in us, by the Spirit which he hath given us - Which witnesses with our spirits that we are his children, and brings forth his fruits of peace, love, holiness. This is the transition to the treating of the Holy Spirit which immediately follows.