Matthew chapter 3 describes the ministry of John the Baptist, who is described as a messenger sent by God to prepare the way for Jesus Christ. John preaches a message of repentance and baptizes those who come to Him, while warning of the coming judgment of God. He encounters the Pharisees and Sadducees, who come to be baptized but are rebuked by John for their lack of true repentance. The chapter also includes the baptism of Jesus by John and the divine affirmation that Jesus is the beloved Son of God.