And when he was demanded of the Pharisees when the kingdom of God should come, he answered them and said, The kingdom of God does not come in a way that you can see. Neither shall they say, Lo here! or, lo there! for, behold, the kingdom of God is within you. (Luke 17:20-21)
The Jewish concept of the kingdom of God of that day was a physical kingdom headquartered in the Jerusalem temple, ruled over by the Messiah. This was also the concept of the disciples – and because of that — every time Jesus spoke of the kingdom of God they interpreted it along those lines. But here Jesus tells us the kind of kingdom He is talking about all through His ministry: Not one you can see, but a spiritual, inward kingdom.
The kingdom of God is the rule or realm of God. It isn’t merely a certain place over which God rules, but rather, it is God’s rule itself – over any person or place. In the OT, God used the idea of a kingdom as a type and shadow — to convey to them what He wanted to reveal to them during that time.
But in the NT, there is a great mystery finally unveiled that was not revealed to prior generations: Christ in you, the hope of glory. (Col. 1:27) WE are the temple of God in which He rules as Lord. Thus, the picture of a kingdom is the picture of the indwelling of the Person of Christ: Christ in you, the hope of glory, is the essence of the kingdom.
Jesus Christ in us equals the kingdom of God in us. Jesus is Lord and King — and the sovereignty that extends from His Person and His Life is the kingdom of God. As for a coming reigning and ruling in the eternal ages, God will only populate His kingdom with those in whom He has established the kingdom through the indwelling of Christ.