Verse 5. - Once more (cf. 1 John 1:7, 9) the opposite is stated and the thought carried further. But whoso keepeth his word (his doctrine as a whole, including the separate commandments), of a truth in him hath the love of God been perfected; i.e., as an accomplished fact; the relation of love has been established. In St. John ἀληθῶς is no mere expletive; it expresses reality, and reality that is known. From verse 4 we might have expected "of a truth he knoweth God;" but the apostle goes beyond this, and shows that really knowing God involves loving him (comp. 1 John 4:11). The context shows that τοῦ Θεοῦ is objective - his love of God rather than God's love of him. The insertion of τοῦ Θεοῦ here, and the drift of the Epistle thus far, are in favour of αὐτόν and αὐτοῦ in verses 3-5 meaning God rather than Christ, although αὐτός in verse 2 tells the other way. The last clause sums up and reaffirms, but as usual with a new turn of thought, the whole section (verses 3-5), which begins and ends with ἐν τούτῳ γινώσκομεν. Knowing God implies keeping his Word; and keeping his Word involves loving him; and all this implies being in him, i.e., having that fellowship with him and his Son in which the Christian's life (which is eternal life) consists, and to promote which St. John publishes his Gospel (1 John 1:3, 4).

2:3-11 What knowledge of Christ can that be, which sees not that he is most worthy of our entire obedience? And a disobedient life shows there is neither religion nor honesty in the professor. The love of God is perfected in him that keeps his commandments. God's grace in him attains its true mark, and produces its sovereign effect as far as may be in this world, and this is man's regeneration; though never absolutely perfect here. Yet this observing Christ's commands, has holiness and excellency which, if universal, would make the earth resemble heaven itself. The command to love one another had been in force from the beginning of the world; but it might be called a new command as given to Christians. It was new in them, as their situation was new in respect of its motives, rules, and obligations. And those who walk in hatred and enmity to believers, remain in a dark state. Christian love teaches us to value our brother's soul, and to dread every thing hurtful to his purity and peace. Where spiritual darkness dwells, in mind, the judgment, and the conscience will be darkened, and will mistake the way to heavenly life. These things demand serious self-examination; and earnest prayer, that God would show us what we are, and whither we are going.But whoso keepeth his word,.... Either the word of the Gospel, and the truths of it, who receives it in love, cordially embraces and retains it, and will by no means part with it, but holds it fast, and stands fast in it; or the precepts and ordinances of the word, who loves these, and esteems them above fine gold, and concerning all things to be right, and observes them as they should be:

in him verily is the love of God perfected: not the love wherewith God loves him, for that is perfect in himself, and admits of no degrees, and cannot be more or less in his heart, and is entirely independent of the obedience of men, or any works of theirs; it is true indeed the manifestations of this love to the saints are imperfect, and may be more and greater, and greater manifestations of love are promised to such that love Christ, and keep his commandments, John 14:21; but here it is to be understood not actively, but passively, of the love wherewith God is loved by his people; and intends not the absolute perfection of it in them, in whom it often waxes cold, and is left, or the fervour of it abated, but the sincerity and reality of it; for by keeping the word of God, both his truths and his ordinances, it is clearly seen that their love to him is without dissimulation, and is not in tongue only, but in deed and in truth:, now it is not the keeping of the word of God that causes this love, or makes it perfect or sincere, for it is a fruit of the Spirit, and is owing to the grace of God; but love, on the other hand, is the cause of keeping of the word; and the latter being a consequent and an effect of the former, is the evidence of it, of the truth and sincerity of it:

hereby know we that we are in him: in Christ, not merely nominally, or by profession, as all that name the name of Christ, and are in a Gospel church state, may be said to be; but really, first secretly, through the love of Christ, the election of God, and the covenant of grace, and then openly, in conversion and the effectual calling, through believing in Christ, when the saints appear to be in him as branches in the vine; and which is known by their fruits, as here, by keeping the word, and doing the commandments of Christ, which do not put a man into Christ, but only show that he is there; for a man's being in Christ is owing to the grace of God; this is the first thing done in grace, 1 Corinthians 1:30.