The book of 3 John consists of a letter written by the apostle John to a man named Gaius. In this letter, John commends Gaius for his faithfulness and hospitality toward fellow believers who have traveled and preached the Gospel. John expresses his joy in hearing about Gaius's commitment to the truth and his support for those who proclaim it.
The letter also addresses an individual named Diotrephes, who is described as arrogant and power-hungry, refusing to acknowledge John's authority and spreading malicious gossip about him. John warns Gaius about Diotrephes and urges him not to imitate his wicked behavior.
Furthermore, John praises another man named Demetrius, who has a good reputation among the believers. John commends Demetrius's character and encourages Gaius to welcome him when he arrives.