No man hath seen God The same words are found in the first chapter of John's Gospel; but John the Baptist had not there exactly the same thing in view, for he meant only that God could not be otherwise known, but as he has revealed himself in Christ. The Apostle here extends the same truth farther, that the power of God is comprehended by us by faith and love, so as to know that we are his children and that he dwells in us. He speaks, however, first of love, when he says, that God dwells in us, if we love one another; for perfected, or really proved to be, in us is then his love; as though he had said, that God shews himself as present, when by his Spirit he forms our hearts so that they entertain brotherly love. For the same purpose he repeats what he had already said, that we know by the Spirit whom he has given us that he dwells in us; for it is a confirmation of the former sentence, because love is the effect or fruit of the Spirit. The sum, then, of what is said is, that since love is from the Spirit of God, we cannot truly and with a sincere heart love the brethren, except the Spirit puts forth his power. In this way he testifies that he dwells in us. But God by his Spirit dwells in us; then, by love we prove that we have God abiding in us. On the other hand, whosoever boasts that he has God and loves not the brethren, his falsehood is proved by this one thing, because he separates God from himself. When he says, and his love is perfected, the conjunction is to be taken as a causative, for, or, because And love here may be explained in two ways, either that which God shews to us, or that which he implants in us. That God has given his Spirit to us, or given us of his Spirit, means the same thing; for we know that the Spirit in a measure is given to each individual.

No man hath seen God at any time - See the notes at John 1:18, where the same declaration occurs. The statement seems to be made here in order to introduce a remark to show in what way we may know that we have any true knowledge of God. The idea is, "He has never indeed been seen by mortal eyes. We are not, then, to expect to become acquainted with what he is in that way. But there is a method by which we may be assured that we have a true knowledge of him, and that is, by evidence that we love another, and by the presence of his Spirit in our hearts. We cannot become acquainted with him by sight, but we may by love."
If we love one another, God dwelleth in us - Though we cannot see him, yet there is a way by which we may be assured that he is near us, and that he even dwells in us. That way is by the exercise of love. Compare the notes at John 14:23-24.
And his love is perfected in us - Is carried out to completion. That is, our love for each other is the proper exponent of love to him reigning in our hearts. The idea here is not that we are absolutely perfect, or even that our love is perfect, whatever may be true on those points, but that this love to others is the proper carrying out of our love toward him; that is, without this our love to him would not have accomplished what it was adapted and designed to do. Unless it produced this effect, it would be defective or incomplete. Compare 1-John 4:17. The general sense is this: "We claim to have the love of God in our hearts, or that we are influenced and controlled by love. But however high and exalted that may seem to be as exercised toward God, it would be defective; it would not exert a fair influence over us, unless it led us to love our Christian brethren. It would be like the love which we might profess to have for a father, if it did not lead us to love our brothers and sisters. True love will diffuse itself over all who come within its range, and will thus become complete and entire." This passage, therefore, cannot be adduced to demonstrate the doctrine of sinless perfection, or to prove that Christians are ever absolutely perfect in this life. It proves only that love to God is not complete, or fully developed, unless it leads those who profess to have it to love each other. See the notes at Job 1:1. On the meaning of the Greek word here used, (τελειόω teleioō,) see the notes at Philippians 3:12. Compare the notes at Hebrews 2:10.

No man hath seen God at any time - The very words, with the change of ἑωρακε for τεθεαται, of this apostle in his gospel, John 1:18. We may feel him, though we cannot see him; and if we love one another he dwelleth in us, and his love is perfected in us - it has then its full accomplishment, having moulded us according to its own nature.

(10) No man hath seen God at any time. If we love one another, God dwelleth in us, and his love is (g) perfected in us.
(10) A third reason: Because God is invisible, therefore by this effect of his Spirit, that is, by charity, he is understood to be not out of us, but united with us and in us, in whom he is so effectually working.
(g) Is surely in us indeed, and in truth.

No man hath seen God at any time,.... The same is said by the Evangelist John, John 1:18; but here it is observed with a different view, and upon another account; there it signifies that no man has seen and looked into the counsels and designs of God, and been able to make a discovery and declaration of his mind and will, his love and grace, and which is there ascribed to the Son of God; see Gill on John 1:18; but here the sense is, that whereas God is invisible in his nature, and incomprehensible in his being and perfections, so that there is no coming to him, and seeing of him, and conversing with him in a familiar way, and so not of loving him as he is in himself, and ought to be loved, as one friend sees, converses with, and loves another, and finds his love increased by sight and conversation; then we ought to love the saints and people of God, who are visible, may be seen, come at, and conversed with, see 1-John 4:20; for this clause stands among the arguments and reasons for brotherly love:
if we love one another God dwelleth in us; not as he does in his Son, by union of nature; nor as in heaven, by the displays of his glory; nor as in the whole world, by his omnipresence and power; but by his Spirit, and the communications of his love, and by his gracious presence and communion, which he indulges the saints with; for such who love one another, as they appear to have the Spirit of God, of which that grace is a fruit, so they are by the Spirit built up a fit habitation for God, and by which Spirit he dwells in them; and such may expect the presence of God, for they who live in peace, the God of love and peace shall be with them:
and his love is perfected in us; not that love of God, with which he loves his people; for that admits of no degrees, and is not more or less in itself, or in his heart; but is always invariably and unchangeably the same, and is full, complete, and perfect in his own breast, as it was from all eternity; and does not pass by degrees, or gradually rise from a love of benevolence to a love of complacency and delight, or increase as our love does to him and to one another, on which it has no dependence: nor is this love perfected in the saints in this life; that is to say, they have not perfect knowledge and enjoyment of it; nor have they all the effects of it bestowed upon them, and applied unto them; the perfection of it, in this sense, will be in heaven: but the love with which God is loved is here designed; and it is called his, because he is both the object and the author of it; and this is no effect as to degrees; yea, sometimes, instead of abounding and increasing, it goes back, it is left, and waxes cold; and it will not have its completion till the saints come to heaven, and then it will be in its full perfection and glory, when faith and hope shall be no more: but the sense is, that this grace of love is sincere and hearty, and without dissimulation; it is unfeigned love; and it is in deed and in truth, and not in word and in tongue only; and this appears to be so, by the love which is shown to the brethren, the children of God; so that love to God in the saints is perfected by love to the brethren, just in such sense as faith is made perfect by works, James 2:22, that is, is made to appear to be genuine, right, and true.

God, whom no man hath seen at any time, hath appointed His children as the visible recipients of our outward kindness which flows from love to Himself, "whom not having seen, we love," compare Notes, 1-John 4:11, 1-John 4:19-20. Thus 1-John 4:12 explains why, instead (in 1-John 4:11) of saying, "If God so loved us, we ought also to love God," he said, "We ought also to love one another."
If we love one another, God dwelleth in us--for God is love; and it must have been from Him dwelling in us that we drew the real love we bear to the brethren (1-John 4:8, 1-John 4:16). John discusses this in 1-John 4:13-16.
his love--rather, "the love of Him," that is, "to Him" (1-John 2:5), evinced by our love to His representatives, our brethren.
is perfected in us--John discusses this in 1-John 4:17-19. Compare 1-John 2:5, "is perfected," that is, attains its proper maturity.

No man hath seen God. He is invisible to mortal eyes, yet we may have a sense of his presence in us. If we love each other he dwells in us.
His love is perfected. It is made complete by our loving each other. It is incomplete unless his love for us is supplemented by brotherly love. This love in us is the proof that God is in us.
Hereby know we, etc. We know that God dwells in us by the Spirit given us. But we know we have the Spirit by its fruits. The first and greatest of these is love. See Galatians 5:22.
We have seen and do testify. See John 15:27. This is John's personal testimony as an apostle.
Whosoever shall confess, etc. In 1-John 4:2 confession of Jesus Christ in word and life is declared proof of the indwelling Spirit; here it is proof of God dwelling in us, which means the same thing.
We know and have believed (Revision). The love of God is a matter of knowledge and was a matter of faith. Love binds us to God.

If we love one another, God abideth in us - This is treated of, 1-John 4:13-16. And his love is perfected - Has its full effect. In us - This is treated of, 1-John 4:17-19.