I wrote unto the church - That is on the former occasion when they went forth. At that time, John naturally commended them to the kind attentions of the church, not doubting but that aid would be rendered them in prosecuting their benevolent work among the Gentiles. The Epistle which was written on that occasion is now lost, and its contents cannot now be ascertained. It was, probably, however, a letter of mere commendation, perhaps stating the object which these brethren had in view, and soliciting the aid of the church. The Latin Vulgate renders this: "scripsissem forsan ecclesiae, "I would have written, perhaps, to the church, but Diotrephes," etc. Macknight also renders this, "I would have written," supposing the sense to be, that John would have commended them to the whole church rather than to a private member, if he had not been aware of the influence and opposition of Diotrephes. The Syriac version also adopts the same rendering. Several manuscripts also, of later date, introduced a particle, (αν an,) by which the same rendering would be demanded in the Greek, though that reading is not sustained by good authority. Against this mode of rendering the passage, the reasons seem to me to be clear.
(1) as already remarked, the reading in the Greek which would require it is not sustained by good authority.
(2) the fair and obvious interpretation of the Greek word used by the apostle, (ἔγραψα egrapsa,) without that particle, is, I "wrote" - implying that it had been already done.
(3) it is more probable that John had written to the church on some former occasion, and that his recommendation had been rejected by the influence of Diotrephes, than that he would be deterred by the apprehension that his recommendation would be rejected.
It seems to me, therefore, that the fair interpretation of this passage is, that these brethren had gone forth on some former occasion, commended by John to the church, and had been rejected by the influence of Diotrephes, and that now he commends them to Gains, by whom they had been formerly entertained, and asks him to renew his hospitality to them.
But Diotrephes, who loveth to have the pre-eminence among them, receiveth us not - Does not admit our authority, or would not comply with any such recommendation. The idea is, that he rejected his interference in the matter, and was not disposed to acknowledge him in any way. Of Diotrephes, nothing more is known than is here specified. Compare the analysis of the Epistle. If he was an officer in the church - a pastor, a ruling elder, a deacon, a vestry-man, a warden, or a private individual - we have no means of ascertaining. The presumption, from the phrase "who loveth to have the pre-eminence," would rather seem to be that he was an aspiring man, arrogating rights which he did not have, and assuming authority to which he was not entitled by virtue of any office. Still he might have held an office, and might have arrogated authority, as many have done, beyond what properly belonged to it.
The single word rendered "who loveth to have the pre-eminence," φιλοπρωτεύων philoprōteuōn, occurs nowhere else in the New Testament. It means simply, "who loves to be first" - meaning that he loved to be at the head of all things, to rule, to lord it over others. It is clearly supposed here, that the church would have complied with the request of the writer if it had not been for this man. What were the alleged grounds for the course which he constrained the church to take, we are not informed; the real ground, the apostle says, was his desire to rule. There may have been at the bottom of it some secret dislike of John, or some private grudge; but the alleged ground may have been, that the church was independent, and that it should reject all foreign interference; or that the church was unable to support those men; or that the work in which they were engaged was one of doubtful propriety.
Whatever was the cause, the case furnishes an illustration of the bad influence of one ambitious and arrogant man in a church. It is often in the power of one such man to bring a whole church under his control, and effectually to embarrass all its movements, and to prevent all the good which it would otherwise accomplish. When it is said, "but Diotrephes receiveth us not," the reference is doubtless to John, and the meaning is, either that he did not acknowledge him as an apostle, or that he did not recognize his right to interfere in the affairs of the church, or that he did not regard his recommendation of these brethren. The first of these suppositions is hardly probable; but, though he may have admitted that he was an apostle, there were perhaps some reasons operating in this particular case why he prevailed on the church to reject those who had been thus commended to their hospitality.

I wrote unto the Church - The Church where Caius was; but Diotrephes, who loveth to have the pre-eminence, φιλοπρωτευων, who loves the presidency, or chief place in the Church. He was doubtless an officer in the Church, at least a deacon, probably a bishop; and, being one, he magnified himself in his office; he loved such eminence, and behaved himself haughtily in it.
Receiveth us not - Does not acknowledge the apostolical authority. As some MSS. supply αν after εγραψα, and several judicious critics believe it is implied, the translation will run thus: I would have written to the Church to receive these men kindly, but Diotrephes, who affects the presidency; and into whose hands, if I wrote to the Church, my letter must come, receiveth us not - would not acknowledge my authority to interfere with any of the matters of his Church; and therefore I have written unto thee, whose love to the brethren and general hospitality are well known, that thou wouldst receive those strangers and persecuted followers of our common Lord.

(2) I wrote unto the church: but Diotrephes, who loveth to have the preeminence among them, receiveth us not.
(2) Ambition and covetousness, two pestilent sins (especially in those who have any church responsibilities) are condemned in Diotrephes.

I wrote unto the church,.... Where Gaius was a member: those who take Gaius to be the same with Paul's host, and whom he baptized at Corinth, think the church at Corinth is here meant; but it seems rather to be meant of some church in Asia nearer Ephesus; nor is it likely that John's first epistle should be here intended, which makes no mention of relieving the brethren, the ministers of the Gospel, that came from Judea: and that this epistle should not be preserved, need not seem strange; for it cannot be thought that everything that was written by him to particular persons, or churches, should be continued. The Alexandrian copy and one of Stephens's read, "I wrote something to the church"; upon this head, concerning receiving and supporting ministers of the Gospel, and so prevents an objection that Gaius might make, why did he not write to the church about it? The Vulgate Latin version reads, "I should", or "would have wrote": and the Syriac version, "I desired", or "wished to have wrote"; suggesting, that though he had not wrote, yet it was much upon his mind, he had a great desire to it:
but Diotrephes, who loveth to have the preeminence among them,
receiveth us not; which hindered him from writing, or was the reason why he wrote now to Gaius since Diotrephes gave no heed to what he had wrote, suppressed his letter, and would not suffer it to be read to the brethren. This Diotrephes, by his name, which signifies one "nourished", or "brought up by Jupiter", was a Gentile; there was one of this name, who was one of the kings of Athens (a); and what may confirm this is, his slighting and rejecting the brethren that came from Judea: it is very likely he was more than a private member in the church, and that he was an officer, and it may be the pastor; and though there is a preeminence, which of right belongs to such an officer, as to preside over the church, to govern, guide, and direct, according to the laws of Christ, he being set over the church, as a ruler, governor, and guide; yet this may be carried too far, as it was by this man, who coveted more than was his due, and lorded it over God's heritage, ruled the flock with force and cruelty, and usurped a tyrannical power over them; whereas every thing in a church ought to be done, by pastor and people, in love, meekness, and with mutual consent. And it may be also, that he sought to have the preeminence over the rest of the elders of the church, for in those large churches there were oftentimes more elders and pastors than one; see Acts 20:17. This ambitious spirit prevailed and obtained among the false teachers, who set up themselves at the head of parties, and above the apostles of Christ, and paved the way for antichrist, who assumed the title of universal bishop, which has introduced all the errors and impieties of the Romish church. Now this man such an ambitious, lordly, and governing spirit, received not the Apostle John, and those that were with him; meaning not their persons, for as yet he and they were not in person where he was; but his letter, his orders, and instructions; these he paid no regard to, concealed them from the church, and would not admit them to be read: or else the apostle's sense is, that he received not the brethren that came from him, and were recommended by him, and whom he affectionately loved, and who were near and dear to him as himself; and therefore not receiving them is interpreted by him as not receiving himself.
(a) Vid. Fabricii Bibliograph. Antiqu. p. 211.

Both the heart and mouth must be watched. The temper and spirit of Diotrephes was full of pride and ambition. It is bad not to do good ourselves; but it is worse to hinder those who would do good. Those cautions and counsels are most likely to be accepted, which are seasoned with love. Follow that which is good, for he that doeth good, as delighting therein, is born of God. Evil-workers vainly pretend or boast acquaintance with God. Let us not follow that which is proud, selfish, and of bad design, though the example may be given by persons of rank and power; but let us be followers of God, and walk in love, after the example of our Lord.

I wrote--The oldest manuscripts add "something": a communication, probably, on the subject of receiving the brethren with brotherly love (3-John 1:8, 3-John 1:10). That Epistle was not designed by the Spirit for the universal Church, or else it would have been preserved.
unto the church--of which Gaius is a member.
loveth . . . pre-eminence--through ambition. Evidently occupying a high place in the Church where Gaius was (3-John 1:10).
among them--over the members of the Church.
receiveth us not--virtually, namely, by not receiving with love the brethren whom we recommended to be received (3-John 1:8, 3-John 1:10; compare Matthew 10:40).

I wrote somewhat unto the church. Of which Gaius was a member. The letter referred to is not extant.
But Diotrephes. This man is not elsewhere named. He was evidently an ambitious and unscrupulous church official, who rebelled against the apostle's authority (receiveth us not), and who refused to heed the letter. The letter may have been sent by those whom Gaius entertained.
Wherefore, if I come. It may be necessary for him to come. If he does, he will arraign Diotrephes for his deeds.
Prating against us. Excusing himself by maligning John.
Neither doth he himself receive the brethren. The messengers John sent.
He forbiddeth. Seeks to prevent any of the church from hearing or extending hospitality to these messengers.
Casting them out of the church. Seeks to have them denied Christian fellowship.
Follow not that which is evil. The wicked example of one like Diotrephes.
Demetrius hath the witness of all. Of this Demetrius we know nothing more. Perhaps he was a member of the same church as Diotrephes, whose example is contrasted.

I wrote to the church - Probably that to which they came. But Diotrephes - Perhaps the pastor of it. Who loveth to have the preeminence among them - To govern all things according to his own will. Receiveth us not - Neither them nor me. So did the mystery of iniquity already work!