Third John and 2 John deal with two sides of the same issue, namely the relationship of the truth and Christian love. In 2 John the writer stressed the importance of the truth. In 3 John he stressed the importance of love. Second John is more general in that it deals with ideas. Third John is more personal and deals with specific cases.
I would summarize the message of this epistle as follows. Brotherly love is the product of abiding in the truth. Let me explain.
John gave two concrete examples to clarify how Christian love that is the product of abiding in the truth (walking in the light) behaves.
The first example is positive and involves Gaius' commendable behavior. Gaius put the needs of others before his own needs and desires. This is how Christian love should behave. It is how Jesus Christ behaved, and it is how He instructed us to behave (Phil. 2:7).
Gaius provided hospitality and financial support for the gospel preachers who visited his town (v. 5).
John approved this practice for three reasons.
1. Such behavior is worthy of God (v. 6). That is, it is in harmony with God's behavior. God provides for those who put His interests before their own (Matt. 6:33).
2. Such behavior is necessary because these men would not get help from unbelievers (v. 7). We should not expect the unsaved to support God's work. If they don't believe the gospel, why would they want to support its propagation?
3. Such behavior makes the supporter a partner with the preacher (v. 8). We really have a share in the work that others do by supporting them materially.
The second example is negative and involves Diotrephes' contemptible behavior. Diotrephes put his personal desires and needs before the needs of others. This is how Christian love should not behave.
The root problem with Diotrephes' behavior was pride, self-centeredness (v. 9). This is the opposite of how Jesus Christ behaved and how He taught us to act.
The fruit product of this attitude was three-fold (v. 10).
1. His words were lies. He was making false accusations against others to elevate himself.
2. His actions were selfish. He was withholding hospitality and support because these acts threatened his own security.
3. His actions toward others were oppressive. He used intimidation to force others to conform to his will rather than submitting to them. He went so far as to exclude others from the fellowship of the church meetings rather than fostering unity among the brethren.
John also gave an exhortation to behave in harmony with the truth (v. 11). He gave two reasons for obeying this exhortation.
First, it is the nature of God's children to do good works (cf. 1 John 3:9; 5:18).
Second, the person who does evil gives evidence that he has not seen God. He is in darkness either as an unbeliever or as a believer (cf. 1 John 1:6).
Finally John gave an opportunity to behave in harmony with the truth (v. 12). This verse underlines the importance of putting love into practice in concrete situations, not just discussing it theoretically.
This brief letter has an important message for the church in our day.
First, we are not really abiding in the truth if we fail to demonstrate love for our brethren in physical, financial ways. We may know the truth intellectually without knowing it experientially. We must not only have it in our grip, but it must also have us in its grip.
Second, our activities reveal our true attitudes. We can see if our attitude is loving or selfish, not by examining our emotions, but by examining our actions. Do our actions demonstrate love or selfishness? This is a very practical and helpful test we should use on ourselves regularly.
