What is the Kingdom of God?

The word translated "kingdom" throughout the New Testament is the Greek word basileia, which denotes "sovereignty, royal power, [and] dominion" (Vine's Complete Expository Dictionary of Old and New Testament Words, "Kingdom"). A careful examination of the Bible reveals that the next phase of the Kingdom of God is nothing short of a world-ruling monarchy that God will establish on this earth through Jesus Christ!
The focus of Jesus Christ's message was the announcement of a coming world government.
A vision explained in the book of Daniel covers prophecies from the time of Daniel to the time of Jesus Christ's second coming. Daniel understood that there would be four major world-ruling empires during that time. Daniel explains that in the days of the fourth empire God will replace these human kingdoms with the Kingdom of God.
"And in the days of these kings the God of heaven will set up a kingdom which shall never be destroyed; and the kingdom shall not be left to other people; it shall break in pieces and consume all these kingdoms, and it shall stand forever" (Daniel 2:44 Daniel 2:44And in the days of these kings shall the God of heaven set up a kingdom, which shall never be destroyed: and the kingdom shall not be left to other people, but it shall break in pieces and consume all these kingdoms, and it shall stand for ever.
American King James Version×). We see that the fourth kingdom continues to rule until Christ returns to establish His Kingdom on earth.
God's Kingdom—foretold repeatedly in Daniel—is the same Kingdom Jesus Christ preached about. The nature of this Kingdom is clear. The four kingdoms described in Daniel 2, 7 and 8 ruled over people and lands. They were great world empires with dominion and power to rule, warring against and conquering other nations. They had kings, governments, laws and subjects. They were literal kingdoms, whose ruins are visible to this day.
So, too, will the Kingdom of God be a literal kingdom ruling over the whole earth. Daniel 7:27 Daniel 7:27And the kingdom and dominion, and the greatness of the kingdom under the whole heaven, shall be given to the people of the saints of the most High, whose kingdom is an everlasting kingdom, and all dominions shall serve and obey him.
American King James Version×, speaking of the establishment of this Kingdom, adds:
"Then the sovereignty, power and greatness of the kingdoms under the whole heaven will be handed over to the saints, the people of the Most High. His kingdom will be an everlasting kingdom, and all rulers will worship and obey him" (New International Version).
The wonderful news of the coming Kingdom of God is the heart and core of Jesus Christ's message for humanity. Jesus will return to earth and establish this Kingdom. He will be the Ruler of the Kingdom of God. Consider this prophecy of Jesus Christ's return: "Then the seventh angel sounded: And there were loud voices in heaven, saying, 'The kingdoms of this world have become the kingdoms of our Lord and of His Christ, and He shall reign forever and ever!'" (Revelation 11:15 Revelation 11:15And the seventh angel sounded; and there were great voices in heaven, saying, The kingdoms of this world are become the kingdoms of our Lord, and of his Christ; and he shall reign for ever and ever.
American King James Version×). Jesus Christ will rule over literal kingdoms on earth.
The governments of mankind, with their inherent inability to solve human problems that are rooted in humanity's inability to choose the right way to live (Proverbs 16:25 Proverbs 16:25There is a way that seems right to a man, but the end thereof are the ways of death.
American King James Version×), will be replaced by a form of government that can at last solve those problems. Jesus Christ Himself will rule the nations of the earth!
This is the gospel—the good news—that Jesus Christ taught. The focus of Jesus Christ's message was the announcement of a coming world government (Luke 21:31 Luke 21:31So likewise you, when you see these things come to pass, know you that the kingdom of God is near at hand.
American King James Version×). This government will not be ruled by selfishly motivated humans but by Jesus Christ Himself, and it will continue forever!