Cotton:

In these words we have Jesus Christ described: -1. By his external function, as being an advocate and a propitiation for our sins. -2. By his inward qualification, as being righteous. We have studied his office of advocate; we come now to his second office. “He is the propitiation for our sins, and not for ours only, but for the sins of the whole world.”

Doct. Jesus Christ is the propitiation for the sins not only of believing Jews, but likewise of believing Christians all the world over.

Some translations render it, “He is the reconciliation; but that does not express the full meaning. Propitiation includes three things.

-1. It requires that he should expiate our sins, that is, make satisfaction for them. A man may be a means of reconciliation without satisfaction, but he cannot be a propitiation without offering satisfaction for the wrong done. Now Christ did make satisfaction for our sins (Heb, 2:17); and to make satisfaction, he offered a satisfactory sacrifice for our sins (1 Pet. 2:24). Since he bore the sin and punishment due to it, it is as much as if we had done it.

-2. To be a propitiation it is required that he make peace and reconciliation; for though a man sometimes may recompense and satisfy a wrong, yet the party wronged will not be at peace with him. But Christ has taken it upon him to reconcile God to us, so that his wrath is turned from us and his favor restored (Col. 1:21). Now this reconciling implies three things: that once we were friends with God, that we fell out with God, and that, having fallen out, we are reconciled again and made at peace with him. Now this last is procured by Christ; whereas we were once friends with God in Paradise, and fell from him and his favor, Christ has come and made up that breach and reconciled us again.

-3. When Christ is said to be a propitiation for our sins, it implies that he has procured the manifestation of God’s favor to us. Suppose a friend makes satisfaction for another, and gets reconcilement with another with whom he is fallen out; yet if the man does not know it, his heart is as heavy as ever. But Christ has not only procured us God’s favor, but he also tells us that his Father is reconciled with us and at peace with us (Job 33:23,26). This is the effect of Christ’s propitiation: we shall see God’s face with joy, and we shall pray to him with comfort. He says himself, “He who loves me shall be loved of my Father” (John 14:21); he will bring them together, and there shall be a mutual expression of love to one another and refreshment in one another. God shall take comfort in us and we in him (Rev. 3: 20), for Christ goes further in this case than any man can.

Absalom had offended his father in slaying his brother Ammon, so he flew away from his father’s court. Joab procured a reconcilement, but he would not satisfy for the blood he had shed. He did indeed procure so much that Absalom was sent home; but yet says David, “Let him return to his own house; he shall not see my faie” (2 Sam. 14:24). Joab could not satisfy for his blood, and thus the king would not see his face; so there lacked complete satisfaction and manifestation of the king’s favor. Afterwards manifestation was procured; but still there lacked propitiation, because satisfaction could not be made. Christ, however, has not only procured favor, but satisfaction as well, and has declared his favor to us in so doing.

Now further, Christ has done this not only for the believing Jews, but all Christians the world over. To whom does he speak here? To “little children”; and who were they? They were Jews, as appears in v. 7, for they from the first giving of the law were commanded to love one another. Now besides these weak Jews, the apostle says he is not only the propitiation for their sins, but for the sins of the whole world.

Now ‘world’ is diversely used in scripture. -1. It is sometimes put for the frame of nature (Acts 17:24). -2. It is sometimes taken for the pleasure and profits of the world (1 John 2: 16). -3. It is sometimes put for the wicked of the world (John 15: 19). -4. It is sometimes taken for the Gentiles in opposition to the Jews (Rom. 11:12). -5. It is sometimes taken for the believers of the world (2 Cor. 5:19). Though it may sometimes have further extent, it is taken in this passage in opposition to Christian Jews; that is, he is not only a propitiation for the Jews, but also for the believing Gentiles.

But further, Christ is not only a propitiation for his children, but for the whole world; that is, the whole body of the creation. By Adam’s fall the whole world was cursed; so Christ by his death renewed the blessing to the world again (Rom. 8:20). Therefore it is said, the whole body of the creation waits for the liberty which the sons of God have. We have a type of this in Noah (Gen. 8:20,21). Noah, as a type of Christ, makes atonement for the world by sacrifice; and God smelled a sweet savor and promised that he would no more curse the earth for man’s sake. And what was done typically in him is perfectly procured in Christ. Christ is now lord of all; he has bought not only us, but our ground and cattle and houses, and our children. And he has so purchased it that the world shall be a blessing to the church; the tumults and disorders shall be for the good of his people.

Has Christ made any propitiation for the wicked? For reprobates? If not, then how for all the world?
-1. You must distinguish between the wicked and the rest of the world. In this they all agree, that Christ is lord over all, wicked and good; he has bought all (2 Pet. 2:1), so that they are vassals to be ruled by Christ’s dominion. He has bought them for the church’s service, to do them good.
-2. I say that Christ has laid down a sufficient price for all, and to this degree he has procured God’s patience to forbear them, and his bounty to lead them to repentance (Rom. 2:4,5), Yea, he has pr them not only gifts fitting them for rule and ministry, and the common gifts and graces, but many sanctifying gifts as well (Heb. 10:29).

But is he then a propitiation for them? I answer, to make propitiation it is required not only that a satisfaction and reconciliation be made, but that they lay hold of it. Under the old law, who had an atonement made by the sacrifices they offered? Only those who laid their hands on the head of the sacrifice (Lev. 1:4). So then this is nothing for the propitiation of the wicked; they do not lay hold on the head of Christ, they do not take hold on him as an advocate and propitiation, and therefore they are left inexcusable. This point is likewise handled by Paul (Rom. 3:25; 2 Cor. 5:19). The whole world was out of fellowship with God, and Christ purchased something for all.

John Cotton, An Exposition of First John (Indiana: Sovereign Grace Publishers, 1962), 82-85.

[Note: A few things are of interest here. Firstly, contra Cotton, see Twisse’s reply to Cotton on 2 Peter 2:1 in his, Treastise of Mr Cottons Clearing certaine Doubts Concerning Predestination (London: Printed by J. D. for Andrew Crook, and are to be sold at his Shop at the Signe of the Green Dragon in Pauls Church0yard, 1646), 255-259. Secondly, Cotton, while orthodox on his doctrines of Predestination, is said to have been a “hypothetical Universalist” (see, Conformity and Orthodoxy in the English Church, c. 1560-1660, edited by Peter Lake and Michael Questier, p., 86).  Cotton’s othodoxy is witnessed to by the fact that he was invited to attend the Westminster Assembly. Thirdly, the question of Cotton’s hypothetical universalism notwithstanding, he has adopted the reading of 1 John 2:2 which is reminiscent of Calvin and Zanchi, which is in itself no evidence of a denial of hypothetical universalism. Lastly, the phrase “to lay down a price” is archaic language to denote, ‘to make a payment for’ etc.]