Don't be like Diotrephes!
I wrote unto the church: but Diotrephes, who loveth to have the preeminence among them, receiveth us not. Wherefore, if I come, I will remember his deeds which he doeth, prating against us with malicious words: and not content therewith, neither doth he himself receive the brethren, and forbiddeth them that would, and casteth them out of the church. 3 John 9-10
Sometimes we not only need an exhortation to do what is right (as in, "Look not every man on his own things, but every man also on the things of others" [Phil. 2:4]), or an example of what doing the right thing looks like (as in, "Let this mind be in you, which was also in Christ Jesus" [Phil. 2:5]), for there are times when we also need an example of the wrong way to do something.
This is so for at least a couple of reasons. Seeing a bad example, rightly observed, will help us to avoid that kind of behavior, and it will also help us to see how wrong and disgusting it is.
This is what should happen when we read this about Diotrephes. Don't be like him! What was his central error? It was that he loved "to have the preeminence" among the saints. He loved to be first, to be the recognized one, to be the celebrated one. It was his way or the highway. As a result, nasty things happened. This is not a neutral attitude, for it led him to speak against one of Christ's apostles "with malicious words" and "not content therewith" he proceeded to excommunicate those who aligned themselves with the apostle.
Brothers and sisters, let us always be wary of the pride that is latent in our hearts, which seeks the preeminence that Diotrephes sought. But nothing good can come of this. And in any case, there is only one in our midst who deserves the preeminence: Jesus Christ (cf. Col. 1:18). Let us not see our own, but the things which are Jesus Christ's (Phil. 2:21). Let him have all the glory.