Two Spiritual Kingdoms
Within the natural and spiritual "realms" there exists natural and spiritual "kingdoms." (The word "kingdom" refers to rulership.) Like the natural realm, the spiritual realm has very real leaders.
The Bible says that the natural kingdoms of this world are under the control of the part of the spiritual kingdom that is evil. The leader of that kingdom is a personality sometimes called Lucifer but more often referred to as "Satan" or "the devil":
Then the devil, taking Him up on a high mountain, showed Him all the kingdoms of the world in a moment of time. And the devil said to Him, "All this authority I will give You, and their glory; for this has been delivered to me, and I give it to whomever I wish." Luke 4:5-6
The kingdom of Satan consists of Satan himself, spiritual beings called demons, and all people who live in sin and rebellion against God. Satan's control, however, is limited and will someday end. God has a plan to change things and bring all the kingdoms of the world under the authority of the kingdom of God:
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 Yahushua Christ and He shall reign forever and ever!" Revelation 11:15
This is......to be put into effect when the times will have reached their fulfillment - to bring all things in heaven and on earth together under one head, even Christ. Ephesians 1:10
God's kingdom consists of God (Father, Son, and Holy Spirit), angels, and all people who live in loving submission to Him.
Every a person alive is a resident of one or the other of these two kingdoms, the kingdom of Satan or the kingdom of God:
Do you do not know that to whom you present yourselves, slaves, to obey, you are that one's slaves whom you obey... Romans 6:16
Changing from the kingdom of Satan to the kingdom of God is done through the agency and finished work of Yahushua Jesus Christ. Accepting Christ as the agent for making a transfer is a choice that has to be made consciously and individually. Any such transfer can be done only through
Yahushua Jesus Christ. He is the one designated by God the Father to handle the legalities in making a change of kingdoms.