Whosoever sinneth hath not seen him. According to his usual manner he added the opposite clause, that we may know that faith in Christ and knowledge of him are vainly pretended, except there be newness of life. For Christ is never dormant where he reigns, but the Spirit renders effectual his power. And it may be rightly said of him, that he puts sin to flight, not otherwise than as the sun drives away darkness by its own brightness. But we are again taught in this place how strong and efficacious is the knowledge of Christ; for it transforms us into his image. So by seeing and knowing we are to understand no other thing than faith.

Whosoever abideth in him - See 1-John 2:6. The word here employed (μένων menōn) properly means to remain, to continue, to abide. It is used of persons remaining or dwelling in a place, in the sense of abiding there permanently, or lodging there, and this is the common meaning of the word, Matthew 10:11; Matthew 26:38; Mark 6:10; Luke 1:56, "et saepe." In the writings of John, however, it is quite a favorite word to denote the relation which one sustains to another, in the sense of being united to him, or remaining with him in affection and love; being with him in heart and mind and will, as one makes his home in a dwelling. The sense seems to be that we have some sort of relation to him similar to that which we have to our home; that is, some fixed and permanent attachment to him. We live in him; we remain steadfast in our attachment to him, as we do to our own home. For the use of the word in John, in whose writings it so frequently occurs, see John 5:38; John 6:56; John 14:10, John 14:17; John 15:27; 1-John 2:6, 1-John 2:10, 1-John 2:14, 1-John 2:17, 1-John 2:27-28; 1-John 3:6, 1-John 3:24; 1-John 4:12-13, 1-John 4:15-16. In the passage before us, as in his writings generally, it refers to one who lives the life of a Christian, as if he were always with Christ, and abode with him. It refers to the Christian considered as adhering steadfastly to the Saviour, and not as following him with transitory feelings, emotions, and raptures.
(See the supplementary note at Romans 8:10. We abide in Christ by union with him. The phrase expresses the continuance of the union; of which see in the note as above. Scott explains, "whoever abides in Christ as one with him and as maintaining communion with him. ')
It does not of itself necessarily mean that he will always do this; that is, it does not prove the doctrine of the perseverance of the saints, but it refers to the adherence to the Saviour as a continuous state of mind, or as having permanency; meaning that there is a life of continued faith in him. It is of a person thus attached to the Saviour that the apostle makes the important declaration in the passage before us, that he does not sin. This is the third argument to show that the child of God should be pure; and the substance of the argument is, that "as a matter of fact" the child of God is not a sinner.
Sinneth not - There has been much difference of opinion in regard to this expression, and the similar declaration in 1-John 3:9. Not a few have maintained that it teaches the "doctrine of perfection," or that Christians may live entirely without sin; and some have held that the apostle meant to teach that this is always the characteristic of the true Christian. Against the interpretation, however, which supposes that it teaches that the Christian is absolutely perfect, and lives wholly without sin, there are three insuperable objections:
(1) If it teaches that doctrine at all, it teaches that all Christians are perfect; "whosoever abideth in him," "whosoever is born of God," "he cannot sin," 1-John 3:9.
(2) this is not true, and cannot be held to be true by those who have any just views of what the children of God have been and are. Who can maintain that Abraham, or Isaac, or Jacob; that Moses, David, or Job; that Peter, John, or Paul, were absolutely perfect, and were never, after their regeneration, guilty of an act of sin? Certainly they never affirmed it of themselves, nor does the sacred record attribute to them any such perfection. And who can affirm this of all who give evidence of true piety in the world? Who can of themselves? Are we to come to the painful conclusion that all who are not absolutely perfect in thought, word, and deed, are destitute of any religion, and are to be set down as hypocrites or self-deceivers? And yet, unless this passage proves that "all" who have been born again are absolutely perfect, it will not prove it of anyone, for the affirmation is not made of a part, or of what any favored individual may be, but of what everyone is in fact who is born of God.
(3) this interpretation is not necessary to a fair exposition of the passage. The language used is such as would be employed by any writer if he designed to say of one that he is not characteristically a sinner; that he is a good man; that he does not commit habitual and willful transgression. Such language is common throughout the Bible, when it is said of one man that he is a saint, and of another that he is a sinner; of one that he is righteous, and of another that he is wicked; of one that he obeys the law of God, and of another that he does not. John expresses it strongly, but he affirms no more in fact than is affirmed elsewhere. The passage teaches, indeed, most important truths in regard to the true Christian; and the fair and proper meaning may be summed up in the following particulars:
(a) He who is born again does not sin habitually, or is not habitually a sinner. If he does wrong, it is when he is overtaken by temptation, and the act is against the habitual inclination and purpose of his soul. If a man sins habitually, it proves that he has never been renewed.
(b) That he who is born again does not do wrong deliberately and by design. He means to do right. He is not willfully and deliberately a sinner. If a man deliberately and intentionally does wrong, he shows that he is not actuated by the spirit of religion. It is true that when one does wrong, or commits sin, there is a momentary assent of the will; but it is under the influence of passion, or excitement, or temptation, or provocation, and not as the result of a deliberate plan or purpose of the soul. A man who deliberately and intentionally does a wrong thing, shows that he is not a true Christian; and if this were all that is understood by "perfection," then there would be many who are perfect, for there are many, very many Christians, who cannot recollect an instance for many years in which they have intentionally and deliberately done a wrong thing. Yet these very Christians see much corruption in their own hearts over which to mourn, and against which they earnestly strive; in comparing themselves with the perfect law of God, and with the perfect example of the Saviour, they see much in which they come short.
(c) He who is born again will not sin finally, or will not fall away. "His seed remaineth in him," 1-John 3:9. See the notes at that verse. There is a principle of grace by which he will ultimately be restrained and recovered. This, it seems to me, is fairly implied in the language used by John; for if a person might be a Christian, and yet wholly fall away and perish, how could it be said with any truth that such a man "sinneth not;" how that "he doth not commit sin;" how that "his seed remaineth in him, and he cannot sin?" Just the contrary would be true if this were so.
Whosoever sinneth - That is, as explained above, habitually, deliberately, characteristically, and finally. - Doddridge. "Who habitually and avowedly sinneth."
Hath not seen him, nor known him - Has had no just views of the Saviour, or of the nature of true religion. In other words, cannot be a true Christian.

Whosoever abideth in him - By faith, love, and obedience.
Sinneth not - Because his heart is purified by faith, and he is a worker together with God, and consequently does not receive the grace of God in vain. See on 1-John 3:3 (note).
Hath not seen him - It is no unusual thing with this apostle, both in his gospel and in his epistles, to put occasionally the past for the present, and the present for the past tense. It is very likely that here he puts, after the manner of the Hebrew, the preterite for the present: He who sins against God doth not see him, neither doth he know him - the eye of his faith is darkened, so that he cannot see him as he formerly did; and he has no longer the experimental knowledge of God as his Father and portion.

Whosoever abideth in him sinneth not: whosoever (h) sinneth hath not seen him, neither known him.
(h) He is said to sin, that does not give himself to purity, and in him sin reigns: but sin is said to dwell in the faithful, and not to reign in them.

Whosoever abideth in him,.... As the branch in the vine, deriving all light, life, grace, holiness, wisdom, strength, joy, peace, and comfort from Christ; or dwells in him by faith, enjoys communion with him as a fruit of union to him; and stands fast in him, being rooted and grounded in him, and abides by him, his truths and ordinances, takes up his rest, and places his security in him, and perseveres through him:
sinneth not; not that he has no sin in him, or lives without sin, but he does not live in sin, nor give up himself to a vicious course of life; for this would be inconsistent with his dwelling in Christ, and enjoying communion with him:
whosoever sinneth; which is not to be understood of a single action, but of a course of sinning:
hath not seen him, neither known him; that is, he has never seen Christ with an eye of faith; he has never truly and spiritually seen the glory, beauty, fulness, and suitableness of Christ, his need, and the worth of him; he has never seen him so as to enjoy him, and have communion with him; for what communion hath Christ with Belial, or light with darkness, or righteousness with unrighteousness? 2-Corinthians 6:14, nor has he ever savingly known him, or been experimentally acquainted with him; for though he may profess to know him in words, he denies him in works.

He reasons from Christ's own entire separation from sin, that those in him must also be separate from it.
abideth in him--as the branch in the vine, by vital union living by His life.
sinneth not--In so far as he abides in Christ, so far is he free from all sin. The ideal of the Christian. The life of sin and the life of God mutually exclude one another, just as darkness and light. In matter of fact, believers do fall into sins (1-John 1:8-10; 1-John 2:1-2); but all such sins are alien from the life of God, and need Christ's cleansing blood, without application to which the life of God could not be maintained. He sinneth not so long as he abideth in Christ.
whosoever sinneth hath not seen him--Greek perfect, "has not seen, and does not see Him." Again the ideal of Christian intuition and knowledge is presented (Matthew 7:23). All sin as such is at variance with the notion of one regenerated. Not that "whosoever is betrayed into sins has never seen nor known God"; but in so far as sin exists, in that degree the spiritual intuition and knowledge of God do not exist in him.
neither--"not even." To see spiritually is a further step than to know; for by knowing we come to seeing by vivid realization and experimentally.

Whosoever abideth in communion with him, by loving faith, sinneth not - While he so abideth. Whosoever sinneth certainly seeth him not - The loving eye of his soul is not then fixed upon God; neither doth he then experimentally know him - Whatever he did in time past.