By this we know that we love the children of God ... - This is repeating the same truth in another form. "As it is universally true that if we love Him who has begotten us, we shall also love His children, or our Christian brethren, so it is true also that if we love His children it will follow that we love Him." In other places, the apostle says that we may know that we love God if we love those who bear His image, 1 John 3:14. He here says, that there is another way of determining what we are. We may have undoubted evidence that we love God, and from that, as the basis of an argument, we may infer that we have true love to His children. Of the fact that we may have evidence that we love God, apart from that which we derive from our love to His children, there can be no doubt. We may be conscious of it; we may find pleasure in meditating on His perfections; we may feel sure that we are moved to obey Him by true attachment to Him, as a child may in reference to a father. But, it may be asked, how can it be inferred from this that we truly love His children? Is it not easier to ascertain this of itself than it is to determine whether we love God? Compare 1 John 4:20. To this it may be answered, that we may love Christians from many motives: we may love them as personal friends; we may love them because they belong to our church, or sect, or party; we may love them because they are naturally amiable: but the apostle says here, that when we are conscious that an attachment does exist toward Christians, we may ascertain that it is genuine, or that it does not proceed from any improper motive, by the fact that we love God. We shall then love Him as His children, whatever other grounds of affection there may be toward them.

And keep his commandments - See the notes at John 14:15.

By this we know that we love the children of God - Our love of God's followers is a proof that we love God. Our love to God is the cause why we love his children, and our keeping the commandments of God is the proof that we love him.

By this we know that we are the children God,.... The Ethiopic version reads, "by this know that we love God"; which, in connection with what follows, makes a tautology, and is a proving "idem per idem": whereas the apostle's view is to show when love to the saints is right; and that is,

when we love God, and keep his commandments: love to the brethren may arise from such a cause, as may show that it is not brotherly love, or of a spiritual kind; it may arise from natural relation, or civil friendship, or from a benefit or favour received from them, and from some natural external excellency seen in them; and a man may do acts of love and kindness to the brethren, from what may be called good nature in himself, or with sinister views; but true love to the brethren springs from love to God: such who love the saints aright, and by which they may know they do so, they love them because they themselves love God, and in obedience to his command; they love them because they belong to God, and are the objects of his love; because his grace is wrought in them, and his image stamped upon them.

By this (ἐν τούτῳ)

Not by this or from this, as an inference (see on 1 John 4:6), but in the very exercise of the sentiment toward God, we perceive.

When (ὅταν)

More strictly, whenever. Our perception of the existence of love to our brethren is developed on every occasion when we exercise love and obedience toward God.

Keep (τηρῶμεν)

Read ποιῶμεν do. So Rev. See on John 3:21; see on 1 John 3:4. The exact phrase ποιεῖν τὰς ἐντολὰς to do the commandments, occurs only here. See on Revelation 22:14.

{2} By this we know that we love the children of God, when we love God, and keep his {c} commandments.

(2) The love of our neighbour depends on the love with which we love God, that this last must go before the first: of which it follows, that that is not to be called love, when men agree together to do evil, neither that, when as in loving our neighbours, we do not respect God's commandments.

(c) There is no love where there is no true doctrine.

5:2 By this we know that we love the children of God. But all born of God must love God's children. The proof that we have this love is that

we love God, and keep his commandments. We so love God as to obey his commandments, one of which is to love our neighbor as ourselves (Le 19:18 Mt 19:19 22:39 Mr 12:31 Ro 13:9 Ga 5:14 Jas 2:8).

5:2 Hereby we know - This is a plain proof. That we love the children of God - As his children.

2. By-Greek, "In." As our love to the brethren is the sign and test of our love to God, so (John here says) our love to God (tested by our "keeping his commandments") is, conversely, the ground and only true basis of love to our brother.

we know-John means here, not the outward criteria of genuine brotherly love, but the inward spiritual criteria of it, consciousness of love to God manifested in a hearty keeping of His commandments. When we have this inwardly and outwardly confirmed love to God, we can know assuredly that we truly love the children of God. "Love to one's brother is prior, according to the order of nature (see on [2649]1Jo 4:20); love to God is so, according to the order of grace (1Jo 5:2). At one time the former is more immediately known, at another time the latter, according as the mind is more engaged in human relations or in what concerns the divine honor" [Estius]. John shows what true love is, namely, that which is referred to God as its first object. As previously John urged the effect, so now he urges the cause. For he wishes mutual love to be so cultivated among us, as that God should always be placed first [Calvin].

5:1-5 True love for the people of God, may be distinguished from natural kindness or party attachments, by its being united with the love of God, and obedience to his commands. The same Holy Spirit that taught the love, will have taught obedience also; and that man cannot truly love the children of God, who, by habit, commits sin or neglects known duty. As God's commands are holy, just, and good rules of liberty and happiness, so those who are born of God and love him, do not count them grievous, but lament that they cannot serve him more perfectly. Self-denial is required, but true Christians have a principle which carries them above all hinderances. Though the conflict often is sharp, and the regenerate may be cast down, yet he will rise up and renew his combat with resolution. But all, except believers in Christ, are enslaved in some respect or other, to the customs, opinions, or interests of the world. Faith is the cause of victory, the means, the instrument, the spiritual armour by which we overcome. In and by faith we cleave to Christ, in contempt of, and in opposition to the world. Faith sanctifies the heart, and purifies it from those sensual lusts by which the world obtains sway and dominion over souls. It has the indwelling Spirit of grace, which is greater than he who dwells in the world. The real Christian overcomes the world by faith; he sees, in and by the life and conduct of the Lord Jesus on earth, that this world is to be renounced and overcome. He cannot be satisfied with this world, but looks beyond it, and is still tending, striving, and pressing toward heaven. We must all, after Christ's example, overcome the world, or it will overcome us to our ruin.