The aged Apostle had written to a church which allowed one Diotrephes to exercise an authority common enough in later ages, but wholly new in the primitive churches. Diotrephes had rejected the apostolic letters and authority. It appears also that he had refused the ministry of the visiting brethren (3John 1:10), and cast out those that had received them.
Historically, this letter marks the beginning of that clerical and priestly assumption over the churches in which the primitive church order disappeared.
This Epistle reveals, as well, the believer's resource in such a day. No longer writing as an apostle, but as an elder, John addresses this letter, not to the church as such, but to a faithful man in the church for the comfort and encouragement of those who were standing fast in the primitive simplicity.
Second John conditions the personal walk of the Christian in a day of apostasy; Third John looks at the personal responsibility, in such a day, of the believer as a member of the local church.
The key-phrase is "the truth" (see 2John, Introduction).
There are four divisions:
I. Personal Greetings. v.1-4
II. Instructions concerning ministering brethren. v.5-8
III. The apostate leader (Diotrephes), and the good Demetrius. v.9-12
IV. Superscription. v.13,14
[The above introduction was adapted from the Scofield Reference Bible, pub. 1917.]
1. The elder unto the wellbeloved Gaius, whom I love in the truth.
John, writing as the last surviving apostle, refers to himself as 'the elder.' cp. 2Joh 1:1a
Gaius (a common Roman name) was a Gentile believer.
Paul mentions one or more men by this name in his epistles. However, due to the late date of John's epistle, it is not possible to identify this man as one of Paul's acquaintances.
The basis, of John's love for Gaius, is their mutual love for 'the Truth.' cp. 2Joh 1:1b,2
As noted in the Book Notes on 2John, 'the Truth' refers (1) to the entirety of God's written Word, and (2) to 'the Truth' of whom the Scriptures speak: the Person and work of the Lord Jesus Christ, in whom true believers place their full confidence (cp. Joh 20:30,31).
2 Beloved, I wish {pray} above {ie., concerning} all things that thou mayest prosper and be in health, even as thy soul prospereth. {Mat 6:33}
3. For I rejoiced greatly, when the brethren came and testified of the truth that is in thee, even as thou walkest in the truth. {cp. 1The 2:19,20}
4 I have no greater joy than to hear that my children walk in truth. {cp. 1Cor 4:15; 2Joh 1:4}
...when the brethren came and testified of the truth that is in thee...
Here is the occasion for this letter. Apparently, a group of traveling ministers (sent or approved by John) had visited the local church where Gaius was a member. They brought back some troubling news concerning the health of the church (v.9-11), but also a good report concerning Gaius, as one who remained sound in doctrine and faithful in living for the Lord. John rejoiced to hear that his spiritual son was walking in the Truth, and prayed that Gaius would be as healthy in body and business as he was in his spiritual life. In the next few verses, John commends Gaius according to what he had heard from the returning brethren.
5 Beloved, thou doest faithfully whatsoever thou doest to the brethren, {cp. Col 3:17; 1Pet 4:10,11} and to strangers {ie., even though they were strangers};
6 Which have borne witness of thy charity {love} before the church: whom if thou bring forward on their journey after a godly sort, {cp. Acts 15:3; Rom 15:24} thou shalt do well:
{ie., ...you will do well to send them on their way in a manner worthy of God. [NASB]}
7 Because that for his name's sake they went forth, taking nothing of the Gentiles.
{cp. 1Cor 9:12-18; Isa 55:1; Rev 22:17}
8 We therefore ought to receive {GK=apolambano, fully welcome} such, {cp. Joh 13:20} that we might be fellowhelpers to {co-laborers for} the truth.
Gaius had welcomed the travelling ministers (though he had not met them before), and had provided them with hospitality (food and lodging). When it was time for them to depart, he sent them off with further provisions for their journey. John commended him for supporting the Lord's servants, noting that by doing so, he was laboring with them in proclaiming the Truth. John encouraged him to continue that good work, as future opportunities would come along.
9. I wrote unto the church: but Diotrephes, who loveth to have the preeminence {the chief place} among them, receiveth {GK=epidechomai, to accept beside (ie., as his peers)} us not. {cf. Mat 20:25-28; Php 2:3-5}
10 Wherefore, if I come, I will remember his deeds which he doeth, {cp. 2Cor 10:1-6} prating {ie., ranting} against us with malicious words: and not content therewith, neither doth he himself receive {GK=epidechomai} the brethren, and forbiddeth them that would, and casteth [them] out of the church. {cp. Luk 6:22; Joh 9:22,34,35}
11 Beloved, follow not that which is evil, but that which is good. {Psa 37:27; Eph 5:1,2} He that doeth good is of God: but he that doeth evil hath not seen God. {1Joh 3:6-11}
John had written to the church (probably to make arrangements for the visit of the travelling ministers). However, Diotrephes had not only assumed full authority over that local church, but also denigrated the aged apostle's authority. Refusing to accept the visiting brothers, he also excommunicated church members who were willing to welcome them. At his next visit, John would put this arrogant man in his place. Meanwhile, he identifies the self-exalting church elder as a man who does not know the Lord (and therefore, a man who should be removed from leadership of the church).
12. Demetrius hath good report of all [men], and of the truth itself: yea, and we [also] bear record; and ye know that our record is true.
The name 'Demetrius' appears on the pages of Scripture, here, and 35 years earlier in Acts 19, where it identified an enemy of the Gospel, who attacked Paul's ministry (Acts 19:24-28). There is no reason to assume any connection between these two men.
All that we know about the godly Demetrius is contained in this one verse. By his witness to the well-known 'good report' concerning this man's reputation, John may be endorsing Demetrius for the office of elder, to shepherd the church, in the place of Diotrephes. (See "must have a good report..." in v.7 of 1Tim 3:1-7.)
13 I had many things to write, but I will not with ink and pen write unto thee:
14 But I trust I shall shortly see thee, and we shall speak face to face. {cp. 2Joh 1:12} Peace [be] to thee. [Our] friends salute thee. Greet the friends by name.