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.

And hereby we do know that we know him - If we keep the commandments of God, loving him with all our heart, and our neighbor as ourselves, we have the fullest proof that we have the true saving knowledge of God and his Christ. The Gnostics pretended to much knowledge, but their knowledge left them in possession of all their bad passions and unholy habits; they, therefore, gave no proof that they had known either God or his Son Jesus - nor is any man properly acquainted with God, who is still under the power of his sins.

And hereby we do know that we know him,.... Either the Father, with whom Christ is an advocate; not as the God of nature, and by the light of it, nor as the lawgiver and Judge of the whole earth, and by the law of Moses; but as the God of all grace, as a God pardoning iniquity, transgression, and sin, as the Father of Christ, and as in him by the Gospel; and this not in a mere notional and speculative way, but with love and affection; not with fear and trembling, as devils know him, nor in theory, as formal professors and hypocrites, but with a knowledge, joined with hearty love of him, and cheerful obedience to him: or else Christ, the advocate and propitiation for sin; and him also, not with a mere notional knowledge of his person and offices, which carnal men and devils themselves have of him, but with that which is spiritual, special, and saving, being from the Spirit and grace of God; and regards Christ as a Saviour, as a propitiatory sacrifice for sin, and an advocate with God the Father; and by which he is approved as such, to the rejection of all other savours, sacrifices, and advocates; and is trusted, confided, and believed in as such, and affectionately loved, and that above all others, in sincerity and truth; and is readily obeyed in his word and ordinances; for where there is true knowledge of Christ, there is faith in him; and where there is faith in him, there is love to him, for faith works by love; and where there is love to him, there will be an observance of his commands; and this is here made the evidence of the true knowledge of him: for it follows,

if we keep his commandments; not the commandments of men, for the keeping of them arises from ignorance of God, and is a proof of it; nor the commandments of the ceremonial law, which are abolished, particularly circumcision, which is opposed to the keeping of the commandments of God, Co1 7:19; but either those of the moral law, and which are more particularly the commandments of God the Father; the observance of which, though it cannot be with perfection, yet being in faith, and from love to God, and with a view to his glory, is an evidence of the true knowledge of him and of his will: or else those commandments, which are more especially the commandments of Christ Jesus; such as the ordinances of baptism and the Lord's supper, which are peculiar to the Gospel dispensation; and which being kept as they were delivered by Christ, and in his name and strength, and to his glory, without depending on them for life and salvation, is an argument and proof of the right knowledge of him; and particularly his new commandment of loving one another may be chiefly designed, that being what the apostle has greatly in view throughout this epistle; now let it be observed, that keeping of the commands of God, or Christ, is not the knowledge of either of them itself, for much may be done in an external way, yet neither God nor Christ be spiritually and savingly known; nor is it the cause of such knowledge, for that is owing to the Spirit and grace of God; but is an effect or consequence of spiritual knowledge, and so an evidence of it; hereby is not the knowledge itself, but the knowledge of that knowledge, that is, that it is true and genuine.

hereby--Greek, "in this." "It is herein," and herein only, that we know (present tense) that we have knowledge of (perfect tense, once-for-all obtained and continuing knowledge of) Him" (Jo1 2:4, Jo1 2:13-14). Tokens whereby to discern grace are frequently given in this Epistle. The Gnostics, by the Spirit's prescient forewarning, are refuted, who boasted of knowledge, but set aside obedience. "Know Him," namely, as "the righteous" (Jo1 2:1, Jo1 2:29); our "Advocate and Intercessor."

keep--John's favorite word, instead of "do," literally, "watch," "guard," and "keep safe" as a precious thing; observing so as to keep. So Christ Himself. Not faultless conformity, but hearty acceptance of, and willing subjection to, God's whole revealed will, is meant.

commandments--injunctions of faith, love, and obedience. John never uses "the law" to express the rule of Christian obedience: he uses it as the Mosaic law.