The New Testament Book of 3 John is the third letter from the Apostle John, who wrote one of the Gospels and the Book of Revelation. This very brief letter, or note, was directed to Gaius, who was a source of joy for John. John also refers to Diotrephes, who was hindering the spread of the gospel for selfish reasons, and to Demetrius, who had a good reputation among the believers.
Gaius is described as walking in the truth, being faithful to his responsibilities, and being known for his love for others.
Diotrephes, however, is described as wanting preeminence, or the prominent place, in the church. He would not receive John and had made malicious statements against him. Diotrephes would not host visiting missionaries and kept others from receiving them into their homes as well.
The third person, Demetrius, who was a Greek convert, had only good things said about him, and he is a good example of Christian character.
This letter should remind us to help spread the good news of Jesus, like Gaius and Demetrius, and not be like Diotrephes, whose selfish ambitions interfered with the work of others.