In John 18:36 Jesus never said, my kingdom will never be on the earth.
Such a statement would destroy the entire Bible at a blow.
What he means is my kingdom doesn’t have its origin in this evil system because currently the whole world lies in the power of the devil.
You find that in 1 John 5:19, the whole world is being deceived. The kingdoms of this world are not, I repeat, not the kingdom of God. And Jesus’ kingdom, which is being prepared now and will be manifest publicly at the second coming, doesn’t have its origin in the wicked systems of the devil. It’s a completely brand new thing.
So it’s not of this system, the Greek word there kosmos, it means the system. It doesn’t belong to the system. And then interestingly, if my kingdom was of satanic origin, then my servants would be fighting and they’re not.
So, this kingdom is a peaceful kingdom, doesn’t work of swords and violence. It’s a different system altogether. And that’s what we’re looking for in the long term. When Christ comes back, he’ll say to the faithful fear, not little flock, it’s my father’s delight and pleasure to give you the kingdom (Luke 12.32, which you may have suffered for in this present life because people don’t like that gospel of the coming kingdom of God on earth and not beyond this earth).