Jesus said, "The kingdom of God is as if someone would scatter seed on the ground, and would sleep and rise night and day, and the seed would sprout and grow, he does not know how. The earth produces of itself, first the stalk, then the head, then the full grain in the head. But when the grain is ripe, at once he goes in with his sickle, because the harvest has come."In these parables, the kingdom of God is something that will grow from a small seed into something great, but we are not going to know exactly how that happens, but that hasn't stopped people from trying to figure it out.
He also said, "With what can we compare the kingdom of God, or what parable will we use for it? It is like a mustard seed, which, when sown upon the ground, is the smallest of all the seeds on earth; yet when it is sown it grows up and becomes the greatest of all shrubs, and puts forth large branches, so that the birds of the air can make nests in its shade."
With many such parables he spoke the word to them, as they were able to hear it; he did not speak to them except in parables, but he explained everything in private to his disciples.
The subject of the Kingdom of God has engaged Christian thinkers for thousands of years with good reason,
The term "Kingdom of God" occurs four times in Matthew (12:28; 19:24; 21:31; 21:43), fourteen times in Mark, thirty-two times in Luke, twice in the Gospel of John (3:3, 5), six times in Acts, eight times in Paul, and once in Revelation (12:10). Matthew actually prefers the term "Kingdom of heaven" which he uses over 20 times in his gospel. (from theopedia.com)In light of so many mentions, why do we have so many questions?
If it were simple, it would not need to be described in parable form.
All human words will ever do at best is to capture a sense of the incomprehensible.
Here is what George Eldon Ladd, "longtime professor at Fuller Seminary and one of the most influential evangelical scholars of the 1900’s", had to say in What is the Kingdom of God?
We must also "seek first his kingdom and his righteousness" (Matt. 6:33). What is the object of our quest? The Church? Heaven? No; we are to seek God's righteousness-His sway, His rule, His reign in our lives.
When we pray, "Thy kingdom come,' are we praying for heaven to come to earth? In a sense we are praying for this; but heaven is an object of desire only because the reign of God is to be more perfectly realized then it is now. Apart from the reign of God, heaven is meaningless. Therefore, what we pray for is, "Thy kingdom come; thy will be done on earth as it is in heaven." This prayer is a petition for God to reign, to manifest His kingly sovereignty and power, to put to fight every enemy of righteousness and of His divine rule, that God alone may be King over all the world.
We pray, "Thy Kingdom come, Thy will be done on earth as it is in heaven." The confidence that this prayer is to be answered when God brings human history to the divinely ordained consummation enables the Christian to retain his balance and sanity of mind in this mad world in which we live. Our hearts go out to those who have no such hope. Thank God, His Kingdom is coming, and it will fill all the earth.
But when we pray, "Thy Kingdom come," we also ask that God's will be done here and now, today. This is the primary concern of these expositions, that the reader might meet the Kingdom of God, or rather, that the Kingdom of God might meet him.
We should also pray, "Thy kingdom come, Thy will be done" in my church as it is in heaven. The life and fellowship of a Christian church ought to be a fellowship of people among whom God's will is done-a bit of heaven on earth. "Thy kingdom come, Thy will be done" in my life, as it is in heaven. This is included in our prayer for the coming of the Kingdom. This is part of the Gospel of the Kingdom of God.When we pray, "Thy kingdom," and "Thy will," we should stress the word "Thy" and humbly confess that too many times we think and act as though it were "my will" and "my kingdom."