When Jesus came proclaiming a kingdom of God, He was speaking of more than a new religious body. Through the many miracles and wonders which God performed through Him, He demonstrated that the rule of God had come, and in some ways had returned to the world. Jesus showed power over every facet of creation and affirmed that the "ruler of this world" was to be cast out.
Despite demonstrating authority over everything on earth and even death and demons, Jesus was rejected by His own and crucified. He had forewarned of this often and even told a parable about His being rejected as King. Jesus still invites people to serve Him in His kingdom, but scripture indicates that far too many will still reject Jesus as their King. In doing so, they forfeit all hope for a future life in the next age.