The “Elder” writes to Gaius and praises him for being cooperative. That is to be in an active relationship with the rest of the body of Christ, to be in covenant with other church as part of the Church. Every congregation, and every Christian for that matter, need to answer for themselves one simple question: How do you relate to the early church?
Every Christian, like Gaius, is called into the fellowship of a congregation and every congregation is called into the fellowship of a denomination.
The “Elder” complains: “Diotrephes, who likes to be their leader, will not pay any attention to what I say.” There have always been non-denominational churches – a very sad concept. A strong personality pulls his own flock together and calls it church. They then are told they do not need to relate to traditional churches. No communication wanted. No extended family wanted. No Christian unity wanted. Just me, myself and I.
In my denomination “each expression of the church is called to honor and respect the work and ministry of each other part. Each expression of the church listens, hears, and carefully considers the advice, counsel, and requests of others.” Now, that is Christian respect and love!