John was cast into prison for his boldness to Herod, which the author describes later (Matthew 14). Jesus withdrew to Galilee after hearing of John’s imprisonment, so he may have wanted to avoid authorities. Galilee was populous and industrious area, and predominantly Gentile. Jesus did not choose a fully Jewish culture with which to begin his ministry. He left his home small village of Nazareth because it rejected him (Luke 4:14-30). This move by Jesus fulfilled the prophecy of Isaiah. Capernaum was a coastal city in Galilee, known for its fishing industry.
Jesus began preaching repentance and the near kingdom of God. We must understand repentance to be a necessity for access to the kingdom. Whereas John the Baptist preached this message also, Jesus fulfilled it.
Jesus chose disciples to teach so they could witness of him and carry on his work. He did not chose the wealthy or the educated. He chose common men, laborers. He called two sets of brothers to gather souls for God. The call of Jesus may not be convenient for us. We may have to put down our nets, and even leave our loved ones behind.
The ministry of Jesus demonstrated authority. Jesus taught with authority. He cast out demons with authority. He healed with authority. The people had never witnessed anything like him, and for this reason word spread quickly and about him, and crowds flocked to him.