Jesus said His Kingdom was not of this world (realm) (John 18:36).  It is a spiritual kingdom, and as such, must never be confused with an Earthly one.  To lose this distinction, even when speaking of a Millennial reign, is an error of great dimension.

The Kingdom is not constituted in books of laws, governmental seating, and minted coinage, and the like.  Yet, on the other end, it is not without potency in the physical dimension.  Consider Jesus’ life and ministry.  He said, to paraphrase, “If I cast out demons by the finger of God, then the Kingdom of God has come upon you.” (Luke 11:20).  The same is true with healing.  Therefore, it was the entrance of the Kingdom which brought about the deliverance in the first place!  Somehow, the invisible, spiritual, and “ethereal” had directly, manifestly affected the natural order.

But, let us not become confused and think carnally, either.  For deliverance and healing are only a small portion of the vastness of the Kingdom.  Consider then, for the Centurion (Matthew 8:5-13)  saw Jesus, and identified with what he saw, that he was a man with authority and a man under authority, so the Kingdom involves much more than simply power, but the fullness of authority as well.  So, it was this Kingdom that Jesus was talking about when He spoke of the Gospel of the Kingdom, and it is this Kingdom that is manifest in a thousand year reign, and it is this Kingdom that is everlasting, nor will be given to another people.  There is no other, there is no addition, there is no change in the nature of this reign.

Any extrapolation of this Kingdom, despite expectations of any parties past, present, or future which deviates from the constituted, recorded and demonstrated reality of this Kingdom, as opposed to a mere mental understanding, is fundamentally flawed, in error, and suffers from the same blindness as plagued the unbelieving Jews of Jesus’ time.

This is, of a fact, the Kingdom referred to when speaking of the Millennium, and this is the Kingdom that all others will submit to, having become the Kingdom of our God and His Christ.  This is the only Kingdom Jesus referred to, the one He operated out of, and, while there may be a physical or organizational structure that is demonstrated through it for a period of time, or buildings, structures, codes of conduct, and other such produced from, through, and to this end, this Kingdom itself is the only the root and true source of these things.  It is the only Kingdom of Heaven, Kingdom of God, and Kingdom of which the Gospel is preached (being, the “Gospel of the Kingdom”, Matthew 24:14) that Jesus both operated in, preached about, and called us to.

To wit, it is neither something “far away”, to wait for, nor is it something to be taken up and “enforced”, as if by arms. As then additionally described by Paul,

For Moses writes that the man who practices the righteousness which is based on law shall live by that righteousness. But the righteousness based on faith speaks as follows: “DO NOT SAY IN YOUR HEART, ‘WHO WILL ASCEND INTO HEAVEN?‘ (that is, to bring Christ down), or ‘WHO WILL DESCEND INTO THE ABYSS?’ (that is, to bring Christ up from the dead).” But what does it say? “THE WORD IS NEAR YOU, IN YOUR MOUTH AND IN YOUR HEART“—that is, the word of faith which we are preaching, that if you confess with your mouth Jesus as Lord, and believe in your heart that God raised Him from the dead, you will be saved;

Romans 10:6-9 (emphasis mine)

This is the door, and this is the road.  It is not by some strategy of man’s world domination, nor is it done through force–for again, if it were of this world, we, His disciples, would be taking up arms to defend it!  But, it is the Eternal Kingdom of the Heavens, the one and only dominion of the Gospel, and, being spiritual, supersedes the physical.

It is this invisible Kingdom that we must apprehend and understand by the Spirit.  It is this, whatever this is, that affected the bodies, and saves the souls of men.  It is not that the message of simple salvation is not enough, for certainly it is, but it is that this invisible dimension must then be grasped, this personal, revealed knowledge of God must the only place in your heart.  In this very real, yet unseen reality, in spirit yet superior to all others, that if we enter into and abide in, we are doing the works of God.  While this may happen in measure to the new believer, we come to maturity by how we grow, and as we believe in greater faith.

If we fail either to apprehend it in this life, or if we transcribe it somehow to something we carry out in the arm of the flesh, in the strength and pride of man or by military or political means, we will have failed to enter into the Kingdom by its very nature, into The Dominion of He Who Is, who is Spirit, and will have begun only working in the flesh.  To whatever measure our understanding and motivation come only from the Earth, what we carry out thus is of absolutely no merit nor lasting worth.  Whether the every day church life, the revival, miracle mandate, the millennial reign, or the Eternal Glory, it must all revolve and center around the center, namely Christ, and reflect the same nature and character of the Kingdom that Christ Himself did.

This then, is how we are to ascertain the precious and the mundane, the secular and the holy.  This is how we are to tell right Eschatalogical understanding from false, by the very narrow door, and the narrow road, called life–and that only when it goes by way of the cross.  For, there is no reigning without suffering, and there is no just assessment without His Kingdom.  For, righteousness and justice are the foundation of His throne.

This Kingdom, the only Kingdom, the Eternal Kingdom.  Not what is visible, but what is invisible.  Not what any plan or efforts of man can produce, but that which God performs when we simply obey Him.

Any eschatalogical, or end times, teaching that fails to grasp the Kingdom here, once for all entrusted to the saints, or a teaching that somehow rewrites the substance of the Kingdom to be of man’s wisdom and efforts, even to the point of  “right doctrine” yet that denies the inherent, substantial, and spiritual reality of that doctrine, or of a physical or social takeover that does not stem only is inherently false, is earthly, soulish, and devoid of faith.  Only the true is capable of producing fruit, and it isn’t up to the pursuer to dictate how or where the pursued should be found.  We must find the door that leads to life, Christ, and we must continue on the narrow road, Faith.  We must believe and keep on believing, and enter in.

It is up to us to find, as Christ finds us, that true expression of His Kingdom by which He cast out demons and healed the sick, to the end that we might be mature, in His nature, and kept in His love.  We must find the substance of that reality which motivated Him, enter in, and believe it to the forsaking of all else, and by that, overcome.

The same faith that started our course will finish it, yet we grow and strengthen in Christ even as we abide.  Yet, as we shed our old selves, and lose what we once thought to be life, we see Him more and more.  Yet, it is this substance, this abiding, which is the very creation of faith, hope, and love that prove to be eternal (1 Corinthians 13:13).  Let us never forget, that this then, is the substance of that, it is the totality of the Kingdom, even as Paul wrote,

For the kingdom of God is . . . righteousness, and peace, and joy in the Holy Ghost.

Romans 14:17 (edited for clarity)

And, when the end of our natural means is there, that is the time to rejoice, be glad, and have no fear.  For, then, ours is this Kingdom.