And ye know that he was manifested, or, hath appeared. He shews by another argument how much sin and faith differ from one another; for it is the office of Christ to take away sins, and for this end was he sent by the Father; and it is by faith we partake of Christ's virtue. Then he who believes in Christ is necessarily cleansed from his sins. But it is said in John 1:29, that Christ takes away sins, because he atoned for them by the sacrifice of his death, that they may not be imputed to us before God: John means in this place that Christ really, and, so to speak, actually takes away sins, because through him our old man is crucified, and his Spirit, by means of repentance, mortifies the flesh with all its lusts. For the context does not allow us to explain this of the remission of sins; for, as I have said, he thus reasons, "They who cease not to sin, render void the benefits derived from Christ, since he came to destroy the reigning power of sin." This belongs to the sanctification of the Spirit. And in him is no sin He does not speak of Christ personally, but of his whole body. [1] Wherever Christ diffuses his efficacious grace, he denies that there is any more room for sin. He, therefore, immediately draws this inference, that they sin not who remain in Christ. For if he dwells in us by faith, he performs his own work, that is, he cleanses us from sins. It hence appears what it is to sin For Christ by his Spirit does not perfectly renew us at once, or in an instant, but he continues our renovation throughout life. It cannot then be but that the faithful are exposed to sin as long as they live in the world; but as far as the kingdom of Christ prevails in them, sin is abolished. In the meantime they are designated according to the prevailing principle, that is, they are said to be righteous and to live righteously, because they sincerely aspire to righteousness. They are said not to sin, because they consent not to sin, though they labor under the infirmity of the flesh; but, on the contrary, they struggle with groaning, so that they can truly testify with Paul that they do the evil they would not. He says that the faithful abide in Christ, because we are by faith united to him, and made one with him.

Footnotes

1 - It is generally taken as referring to Christ personally; he being mentioned here as having no sin, because he is in this respect an example to his people; or, according to some, because he was thereby fitted for the office of taking away our sins; or, because he had no sin of his own to take away. Grotius viewed the present as used here for the past tense, -- "and sin was not in him." See a similar instance in John 15:27 -- Ed.

And ye know that he was manifested - The Lord Jesus, the Son of God. "You know that he became incarnate, or appeared among people, for the very purpose of putting an end to sin," Matthew 1:21. Compare the notes at 1-Timothy 3:16. This is the "second" argument in this paragraph, 1-John 3:4-10, by which the apostle would deter us from sin. The argument is a clear one, and is perhaps the strongest that can be made to bear on the mind of a true Christian - that the Lord Jesus saw sin to be so great an evil, that he came into our world, and gave himself to the bitter sorrows of death on the cross, to redeem us from it.
To take away our sins - The essential argument here is, that the whole work of Christ was designed to deliver us from the dominion of sin, not to furnish us the means of indulgence in it; and that, therefore, we should be deterred from it by all that Christ has done and suffered for us. He perverts the whole design of the coming of the Saviour who supposes that his work was in any degree designed to procure for his followers the indulgences of sin, or who so interprets the methods of his grace as to suppose that it is now lawful for him to indulge his guilty passions. The argument essentially is this:
(1) That we profess to be the followers of Christ, and should carry out his ends and views in coming into the world;
(2) that the great and leading purpose of his coming was to set us free from the bondage of transgression;
(3) that in doing this he gave himself up to a life of poverty, and shame, and sorrow, and to a most bitter death on the cross; and,
(4) that we should not indulge in that from which he came to deliver us, and which cost him so much toil and such a death. How could we indulge in that which has brought heavy calamity upon the head of a father, or which has pierced a sister's heart with many sorrows? Still more, how can we be so ungrateful and hardhearted as to indulge in that which crushed our Redeemer in death?
And in him is no sin - An additional consideration to show that we should be holy. As he was perfectly pure and spotless, so should all his followers aim to be; and none can truly pretend to be his who do not desire and design to become like him. On the personal holiness of the Lord Jesus, see the Hebrews 7:26 note, and 1-Peter 2:23 note.

And ye know that he was manifested to take away our sins - He came into the world to destroy the power, pardon the guilt, and cleanse from the pollution of sin. This was the very design of his manifestation in the flesh. He was born, suffered, and died for this very purpose; and can it be supposed that he either cannot or will not accomplish the object of his own coming?
In him is no sin - And therefore he is properly qualified to be the atoning sacrifice for the sins of men.

(6) And ye know that he was manifested to take away our sins; and in him is no sin.
(6) An argument taken from the material cause of our salvation: Christ in himself is most pure, and he came to take away our sins, by sanctifying us with the Holy Spirit, therefore whoever is truly a partaker of Christ, does not give himself to sin, and on the contrary, he that gives himself to sin does not know Christ.

And ye know that he was manifested,.... This is a truth of the Gospel the saints were well instructed in and acquainted with; that Jesus Christ, the Word and Son of God, who is here meant, who was with the Father, and lay in his bosom from all eternity, was in the fulness of time made manifest in the flesh, or human nature, by assuming it into union with his divine person; in which he came and dwelt among men, and became visible to them: the end of which manifestation was,
to take away our sins; as the antitype of the scape goat, making reconciliation and satisfaction for them, through the sacrifice of himself; which was doing what the blood of bulls and goats, or any legal sacrifices or moral performances, could never do: and this he did by taking the sins of his people upon himself, by carrying them up to the cross, and there bearing them, with all the punishment due unto them, in his body; by removing them quite away, and utterly destroying them, finishing and making an end of them: and by causing them to pass away from them, from off their consciences, through the application of his blood by his Spirit:
and in him is no sin; neither original, nor actual; no sin inherent; there was sin imputed to him, but none in him, nor done by him; and hence he became a fit person to be a sacrifice for the sins of others, and by his unblemished sacrifice to take the away; and answered the typical sacrifices under the law, which were to be without spot and blemish: and this shows that he did not offer himself for any sins of his own, for there were none in him, but for the sins of others; and which consideration, therefore, is a strong dissuasive from sinning, and as such is mentioned by the apostle; for, since sin is of such a nature that nothing could atone for it but the blood and sacrifice of Christ, an innocent, as well as a divine person, it should be abhorred by us; and since Christ has taken it away by the sacrifice of himself, it should not be continued and encouraged by us; and since in him is no sin, we ought to imitate him in purity of life and conversation; the end of Christ's bearing our sins was, that we might live unto righteousness, and to purify to himself a peculiar people, zealous of good works; and his love herein should constrain us to obedience to him: so the Jews (l) speak of a man after the image of God, and who is the mystery, of the name Jehovah; and in that man, they say, there is no sin, neither shall death rule over him; and this is that which is said, Psalm 5:4; neither shall evil dwell with thee.
(l) Sepher Tikkunim, fol. 112. 1. apud Rittangel, de ver. Rel. Christ, p. 68.

Additional proof of the incompatibility of sin and sonship; the very object of Christ's manifestation in the flesh was to take away (by one act, and entirely, aorist) all sins, as the scapegoat did typically.
and--another proof of the same.
in him is no sin--not "was," but "is," as in 1-John 3:7, "He is righteous," and 1-John 3:3, "He is pure." Therefore we are to be so.

And ye know that he - Christ. Was manifested - That he came into the world for this very purpose. To take away our sins - To destroy them all, root and branch, and leave none remaining. And in him is no sin - So that he could not suffer on his own account, but to make us as himself.