I. Diotrephes, unlike Gaius, loved preeminence and refused apostolic authority, spreading malicious words. He did not accept John’s letter and discouraged others from showing hospitality, casting them out of the church. John warns that he will address this behavior when he visits. II. John cautions against following Diotrephes’ evil example and encourages believers to imitate what is good, for those who do good are of God, while those who do evil have not seen God.

If I come, I will remember - I will show him the authority which, as an apostle of Jesus Christ, I possess.
Prating against us - Diotrephes might have been a converted Jew, who was unwilling that the Gentiles should be received into the Church; or a Judaizing Christian, who wished to incorporate the law with the Gospel, and calumniated the apostles who taught otherwise. This haughty and unfeeling man would give no countenance to the converted Gentiles; so far from it, that he would not receive any of them himself, forbade others to do it, and excommunicated those who had been received into the Church by the apostles. This appears to be the meaning of neither doth he himself receive the brethren, and forbiddeth them that would, and casteth them out of the Church. He had the complete dog in the manger principle: he would neither do, nor let do; and when good was done that he did not approve, he endeavored to undo it.

Wherefore, if I come,.... Where both Gaius and Diotrephes lived, as he trusted he should shortly, Jo3 1:14;

I will remember his deeds which he doth; meaning, not only that he would tell him of them to his face, but make mention of them, and expose them to the whole church, and reprove him for them: and which are as follow,

prating against us with malicious words; it is a common thing for ministers of the Gospel to be prated against, not only by the men of the world, but by professors of religion, and by such who call themselves preachers also; nor need it be wondered at, since John, an apostle of Christ, the beloved disciple, who was so harmless and inoffensive in his conversation, so kind and loving in his disposition and temper, so meek and humble in his deportment, and now in such an advanced age, was prated against by a Diotrephes: and what is said against Christ's ministers is no other than prating; silly, idle, trifling, and empty stuff, as the word used signifies; for want of greater things, they take up any little matter, and improve it against them; and this is often done with a malicious intent, to hurt their characters, spoil their usefulness, and render their ministry unprofitable.

And not content herewith; with prating against the Apostle John, and the ministers with him, in this wicked way:

neither doth he himself receive the brethren; the meaning is not, that he did not receive them into the church, for they were there, since afterwards mention is made of his casting them out from thence; but he did not receive them into his house, and entertain them as he ought to have done; for a minister of the Gospel, and a pastor of a church, ought to be hospitable, and given to hospitality, and entertain strangers, especially those who are brethren in Christ, and fellow ministers of the word: and the rather these were to be received, since they travelled about to spread the Gospel among the Gentiles, and took nothing of them. And this was not all, he not only did not receive them himself, and reject them, but was not willing that others should receive them:

and forbiddeth them that would; on such who had a heart, as well as ability, to receive and entertain these poor brethren, he laid his injunctions, and gave them strict orders, in his lordly and tyrannical way, not to show any respect unto them;

and casteth them out of the church; that is, he excommunicated them, either those that entertained them, or rather the brethren themselves; which was an abuse of the ordinance of excommunication, as that ordinance is abused, when any single person, a pastor, or any other, as here, assumes the power of doing it himself, and does it without the church; whereas it is a punishment or censure, to be inflicted by many, or to be done by the joint suffrage of the church; and when it is done in a wrong cause, for some small trifling matter, or none at all, and not in a case of heresy or immorality, obstinately persisted in; and when it is done from wrong principles, and with wrong ends, as to gratify the pride and passion of some; and not for the good of the person cast out, or to prevent others from falling into the same snare, or for the honour of religion, and the glory of God. The phrase seems to be taken from the Jews, who expressed their excommunication, or putting out of the synagogue, by a casting out; see Joh 9:34.

if I come-- (Jo3 1:14).

I will remember--literally, "I will bring to mind" before all by stigmatizing and punishing.

prating--with mere silly tattle.

neither doth he . . . receive the brethren--with hospitality. "The brethren" are the missionaries on their journey.

forbiddeth them that would--receive them.

casteth them--those that would receive the brethren, by excommunication from the Church, which his influence, as a leading man (Jo3 1:9) in it, enabled him to do. NEANDER thinks that the missionaries were JEWS by birth, whence it is said in their praise they took nothing from THE GENTILES: in contrast to other Jewish missionaries who abused ministers' right of maintenance elsewhere, as Paul tells us, Co2 11:22; Phi 3:2, Phi 3:5, Phi 3:19. Now in the Gentile churches there existed an ultra-Pauline party of anti-Jewish tendency, the forerunners of Marcion: Diotrephes possibly stood at the head of this party, which fact, as well as this domineering spirit, may account for his hostility to the missionaries, and to the apostle John, who had, by the power of love, tried to harmonize the various elements in the Asiatic churches. At a later period, Marcion, we know, attached himself to Paul alone, and paid no deference to the authority of John.