What does Matthew 4:17 mean?

Matthew emphasizes in this verse that Jesus' ministry became entirely established after His move to Capernaum. He fully embraced the mission the Father had given to Him and began to preach to the people of Israel. Matthew shows that Jesus' ministry began in earnest after the arrest of John the Baptist.

Jesus' preaching ministry begins with the same essential message as John the Baptist: Repent, for the kingdom of heaven is near (Matthew 3:1–2). There is a difference, though. John preached that message to Israel as the one who prepared the way for the coming of the Messiah. He called the people to get ready, before the Messiah arrived and established the kingdom of heaven.

Jesus preached the same message, but He did so as the Messiah Himself. He called people to repent, but He would also call them to submit to and follow Him as the Son of God. Both John and Jesus emphasized that people cannot participate in God's kingdom without first repenting of their sins, changing the course of their lives to follow the way of Christ.