MATHEW 4:17
From that time Jesus began to preach and to say, “Repent, for the kingdom of heaven is at hand.
The Kingdom of heaven is right here with us. It dwells in you and me through the Holy Spirit, who is the governor in the Kingdom of God.
After Jesus was baptized at river Jordan, the Kingdom of heaven came upon him through the sign of a dove-the Holy Spirit of God came upon him. Soon after he conquered the temptations of the devil in the wilderness, he began to preach. His first message was about repentance, changing our ways of thinking and actions for the Kingdom of God is here.
John the Baptist also spoke about the Kingdom of God and he preached the same message before Jesus came.
Mathew 3:1-2
“In those days John the Baptist came, preaching in the wilderness of Judea and saying “Repent [change your inner self—your old way of thinking, regret past sins, live your life in a way that proves repentance], for the kingdom of heaven is at hand.”