The Tale of Diotrephes

3Jn 1:9  I wrote something to the church, but Diotrephes, who loves to be first among them, does not acknowledge us.  
3Jn 1:10  Therefore, if I come, I will call attention to the deeds he is doing — the bringing of unjustified charges against us with evil words! And not being content with that, he not only refuses to welcome the brothers himself, but hinders the people who want to do so and throws them out of the church! 
3Jn 1:11  Dear friend, do not imitate what is bad but what is good. The one who does good is of God; the one who does what is bad has not seen God.

From the Believers Bible Commentary on verse 9.

Apparently John had written along this line to the church, but his Letter was intercepted by a man named Diotrephes, who had an exaggerated view of his own importance. He was a virtual dictator in the assembly. His sin was pride of place, an inflated ego, and a violent jealousy for what he regarded as his own rights—which he doubtless defended as the autonomy of the local church. Diotrephes had forgotten that Christ is the Head of the church—if he ever knew it! He had forgotten that the Holy Spirit is the Vicar or Representative of Christ in the church. No mere man has the right to take charge, to make decisions, to receive, or to refuse. Such conduct is popery, and God hates it. Doubtless Diotrephes excused his behavior on the ground that he was contending for the truth. But that was, of course, a lie! He was doing untold harm to the truth by refusing the apostle on the pretext of being faithful to God. And not only John, but other brethren as well.