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.

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].