Question No. 45:—Since Jesus says “the kingdom of God is within” us (Luke 17:21), how, then, can it be an earthly kingdom? — {2ANS 89.3}
Answer:—If the statement in question means that there is to be no Kingdom of God on earth, then by the same token of reasoning it must also mean that neither is there to be any kingdom in heaven. And if there is to be none on earth, and none in heaven, then our hope is vain. But, as always, that which proves too much, proves nothing. Consequently, to stand upon the proposition in the question is to take the position that there is to be no literal kingdom either on earth or in heaven, but only a spiritual kingdom within the heart, which is to reduce the subject to an absurdity. It is to play right into the hands of the Devil, who would desperately like to blackout the Kingdom truth, and relegate the Kingdom itself to oblivion. But in this, thank God, the Word assures us he is doomed to certain failure. — {2ANS 89.4}
So before the Kingdom of God is established on this earth, it must indeed be spiritually established within us if we are ever to qualify for admission when it is physically established upon “earth, as it is in heaven.” — {2ANS 90.1}
Accordingly, the spiritual kingdom of God within, is within those who embody the principles of its rule before the physical Kingdom is established. So the kingdom of God “within” is the regimen of the spiritual life; it is prerequisite to an inheritance in the external Kingdom of God. — {2ANS 90.2}