These verses may seem to relate to the seventh verse of the former chapter, between which and these verses there occurred an incidental discourse concerning the believer's duty and relief in case of sin, occasioned by the mention of one of the believer's privileges - his being cleansed from sin by the Mediator's blood. In that verse the apostle asserts the beneficial consequence of walking in the light: "We have then fellowship with one another, such divine fellowship and communion as are the prerogative of the church of Christ." Here now succeeds the trial or test of our light and of our love.

I.The trial of our light: And hereby we do know that we know him, if we keep his commandments, Jo1 2:3. Divine light and knowledge are the beauty and improvement of the mind; it becomes the disciples of the Mediator to be persons of wisdom and understanding. Young Christians are apt to magnify their new light and applaud their own knowledge, especially if they have been suddenly or in a short time communicated; and old ones are apt to suspect the sufficiency and fulness of their knowledge; they lament that they know God, and Christ, and the rich contents of his gospel, no more: but here is the evidence of the soundness of our knowledge, if it constrain us to keep God's commandments. Each perfection of his nature enforces his authority; the wisdom of his counsels, the riches of his grace, the grandeur of his works, recommend his law and government. A careful conscientious obedience to his commands shows that the apprehension and knowledge of these things are graciously impressed upon the soul; and therefore it must follow in the reverse that he that saith, I know him, and keepeth not his commandments, is a liar, and the truth is not in him, Jo1 2:4. Professors of the truth are often ashamed of their ignorance, or ashamed to own it; they frequently pretend to great attainments in the knowledge of divine mysteries: Thou makest thy boast of God, and knowest his will, and approvest (in thy rational judgment) the things that are more excellent, being instructed out of the law and art confident that thou thyself art (or art fit to be) a guide to the blind, etc., Rom 2:17, etc. But what knowledge of God can that be which sees not that he is most worthy of the most entire and intense obedience? And, if that be seen and known, how vain and superficial is even this knowledge when it sways not the heart unto obedience! A disobedient life is the confutation and shame of pretended religious knowledge; it gives the lie to such boasts and pretences, and shows that there is neither religion nor honesty in them.

II.The trial of our love: But whoso keepeth his word in him verily is the love of God perfected; hereby know we that we are in him, Jo1 2:5. To keep the word of God, or of Christ, is sacredly to attend thereto in all the conduct and motion of life; in him that does so is the love of God perfected. Possibly, some may here understand God's love to us; and doubtless his love to us cannot be perfected (or obtain its perfect design and fruit) without our practical observance of his word. We are chosen, to be holy and blameless before him in love; we are redeemed, to be a peculiar people, zealous of good works; we are pardoned and justified, that we may be partakers of larger measures of the divine Spirit for sanctification; we are sanctified, that we may walk in ways of holiness and obedience: no act of divine love that here terminates upon us obtains its proper tendency, issue, and effect, without our holy attendance to God's word. But the phrase rather denotes here our love to God; so Jo1 2:15, The love of (to) the Father is not in him; so Jo1 3:17, How dwelleth the love of (to) God in him? Now light is to kindle love; and love must and will keep the word of God; it enquires wherein the beloved may be pleased and served, and, finding he will be so by observance of his declared will, there it employs and exerts itself; there love is demonstrated; there it has its perfect (or complete) exercise, operation, and delight; and hereby (by this dutiful attendance to the will of God, or Christ) we know that we are in him (Jo1 2:5), we know that we belong to him, and that we are united to him by that Spirit which elevates and assists us to this obedience; and if we acknowledge our relation to him, and our union with him, it must have this continued enforcement upon us: He that saith he abideth in him ought himself to walk even as he walked, Jo1 2:6. The Lord Christ was an inhabitant of this world, and walked here below; here he gave a shining example of absolute obedience to God. Those who profess to be on his side, and to abide with him, must walk with him, walk after his pattern and example. The partisans of the several sects of philosophers of old paid great regard to the dictates and practice of their respective teachers and sect-masters; much more should the Christian, he who professes to abide in and with Christ, aim to resemble his infallible Master and head, and conform to his course and prescriptions: Then are you my friends if you do whatsoever I command you, Joh 15:14.

But whoso keepeth his word - Conscientiously observes his doctrine, the spirit and letter of the religion of Christ.

Is the love of God perfected - The design of God's love in sending Jesus Christ into the world to die for the sin of man τετελειωται, is accomplished, in that man who receives the doctrine, and applies for the salvation provided for him. This seems to be the meaning of the apostle.

That we are in him - That we have entered into his spirit and views, received his salvation, have been enabled to walk in the light, and have communion with him by the Holy Spirit.

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, Joh 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, Co1 1:30.

Not merely repeating the proposition, Jo1 2:3, or asserting the merely opposite alternative to Jo1 2:4, but expanding the "know Him" of Jo1 2:3, into "in Him, verily (not as a matter of vain boasting) is the love of (that is towards) God perfected," and "we are in Him." Love here answers to knowledge in Jo1 2:3. In proportion as we love God, in that same proportion we know Him, and vice versa, until our love and knowledge shall attain their full maturity of perfection.

his word--His word is one (see on Jo1 1:5), and comprises His "commandments," which are many (Jo1 2:3).

hereby--in our progressing towards this ideal of perfected love and obedience. There is a gradation: Jo1 2:3, "know Him"; Jo1 2:5, "we are in Him"; Jo1 2:6, "abideth in Him"; respectively, knowledge, fellowship, abiding constancy. [BENGEL].