Jesus began His earthly ministry by teaching about the imminence of the kingdom. That being the case, many would probably ask, what happened to that promised kingdom. Why is it not more in evidence?
In response to these questions, I have heard a couple of proposed answers. One line of thought says that the Jewish rejection of Jesus caused God to postpone the kingdom coming and insert the church age as an interim measure to bridge the period of history between the cross and the return of Christ, when the kingdom will then be established on earth as originally proclaimed. A second explanation says that the church is the kingdom on earth but only in a limited sense, because the full kingdom blessings await the return of Christ in our future when the kingdom will reach its consummation in heaven. Either of these two responses implies that the promise of the kingdom is yet unfulfilled in the ultimate sense.
With the emphasis on the coming of the kingdom that we read about throughout the teachings of Jesus, a yet unfulfilled kingdom is troubling to say the least. A delayed or incomplete kingdom promise implies that despite the death, burial, and resurrection, that Jesus did not complete His mission. Sin and death have not been dealt with totally because a future event is yet required. The fact that the final step in eliminating these two banes to human existence involves a cataclysmic destruction only increase the uneasiness associated with a kingdom which remains so unrealized so many long years after its announcement. Could God's plan really be overthrown by recalcitrant men? Could the final solution to man's malfeasance really be his destruction, even after Christ died for the ungodly. Is death to be conquered by assigning most men to a second death? None of these questions have ready answers within traditional Christian theology.
No doubt some will note that Jesus said that the kingdom is within us. That being the case, maybe we don't realize the kingdom's existence and associated blessings because we seek it outside of ourselves, in the various churches with their numerous dogmas and rituals. Looking in the wrong direction could conceivably cause us collectively to miss something that already exists but not in the fashion we have been taught.
Of course, this explanation still fails to address the apparent lack of full kingdom blessings for all mankind. No matter how one tries to go, the question of unrealized transformation remains to challenge our understanding of the promised kingdom.