| Barnes' Notes on the Bible He that saith, I know Him - He who professes to be acquainted with the Saviour, or who professes to be a Christian. And keepeth not his commandments - What he has appointed to be observed by his people; that is, he who does not obey him. Is a liar - Makes a false profession; professes to have that which he really has not. Such a profession is a falsehood, because there can be no true religion where one does not obey the law of God.
Clarke's Commentary on the BibleHe that saith, I know him - This is a severe blow against those false teachers, and against all pretenders to religious knowledge, who live under the power of their sins; and against all Antinomians, and false boasters in the righteousness of Christ as a covering for their personal unholiness. They are all liars, and no truth of God is in them.
Gill's Exposition of the Entire BibleHe that saith I know him,.... God or Christ, as the Gnostics did, who pretended to great, even perfect, knowledge of divine things: and keepeth not his commandments; which the above persons had no regard to, and as many who profess great light and knowledge in our days show no concern for: is a liar; he contradicts what he says, and gives the lie to it; for though in words he professes to know God, in works he denies him, and which betrays his ignorance of him: and the truth is not in him; there is no true knowledge of God and Christ in him; nor is the truth of the Gospel in his heart, however it may be in his head; nor is the truth of grace in him, for each of these lead persons to obedience. The Ethiopic version renders it, "the truth of God is not with him"; See Gill on 1 John 1:8.
Vincent's Word StudiesA liar Compare we lie, 1 John 1:6. In him (ἐν τούτῳ) Emphatic. Lit., in this one the truth is not. See on 1 John 1:8.
Geneva Study Bible{3} He that saith, I know him, and keepeth not his commandments, is a liar, and the truth is not in him. (3) Holiness, that is, a life ordered according to the prescript of God's commandments, however weak we are, is of necessity joined with faith, that is, with the true knowledge of the Father in the Son.
People's New Testament 2:4 He that saith, etc. If one claims to have a saving knowledge of Christ, yet lives in disobedience, his life puts the lie to his words.
Jamieson-Fausset-Brown Bible Commentary4. I know-Greek, "I have knowledge of (perfect) Him." Compare with this verse 1Jo 1:8.
Matthew Henry's Concise Commentary2:3-11 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.
Matthew Henry's Whole Bible CommentaryVerses 3-6 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, v. 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, v. 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, v. 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 v. 15, The love of (to) the Father is not in him; so ch. 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 (v. 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, v. 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, Jn. 15:14. | 
