It is of tremendous importance to realize that at the very beginning there were two trees—the tree of life and the tree of the knowledge of good and evil (Gen. 2:9). The tree of life signifies God, and the tree of knowledge signifies Satan. Man took the tree of knowledge into him, meaning that Satan entered into man. Satan, as sin personified, is now inside of man (Rom. 7:8, 11, 17, 20). After coming into man, Satan began to saturate him, poison him, and take full possession of him. Thus, man became corrupted and darkened. To be darkened and corrupted by Satan means to be placed under the authority of Satan. Man became a citizen in Satan’s kingdom, subject to the rule of Satan. Everyone born of man is likewise a citizen in Satan’s kingdom. Every human being is subject to Satan by birth. Therefore, men steal, fight, and kill. This is the kingdom of Satan. This is the totality of the satanic life with all its activities.
One day Jehovah-plus came. God was incarnated as a man. God’s desire is to come into man. When we call on the name of the Lord Jesus, He comes into us as life. From that point on, God grows within us. God’s growth in us means that He is spreading within us. The more God grows, the more He spreads, and the more ground He occupies within us. The more ground He occupies, the more He reigns. The kingdom is God’s divine reign in us through the inward growth of life. The kingdom of God is God being life to us, spreading in us, occupying the ground in us, and reigning over our whole being.
There are two kingdoms, and there are two spirits. John 4:24 shows that God is a Spirit, and Ephesians 2:2 reveals that Satan, the ruler of the authority of the air, is also a spirit. This evil spirit is working in every human being. The word "working" is a strong word in Greek, and some versions render it as "operating." Satan is operating, working, with a definite purpose in a definite way. In every human being there is a satanic operator, the spirit who works in the sons of disobedience. People may talk about freedom, liberty, and independence. Everyone likes to be independent. However, not one fallen person is independent, because he is under the operation of Satan.
THE RULER OF THIS WORLD
Matthew 12:26 indicates that Satan has a kingdom, and John 12:31 describes Satan as the ruler of this world. Satan is not only the operator; he is the ruler. He rules the whole earth, and he has many subordinates, many ranks, under him, which Ephesians 6:12 describes as rulers and authorities. These are some of the various ranks in Satan’s kingdom. He is the ruler of this world, and he is also the ruler of the authority of the air. On the earth there is the human race, and in the air there are the rebellious angelic powers. Satan’s kingdom is composed of the fallen human race and the rebellious angels. On the earth, the fallen human race are the citizens of the kingdom of Satan; in the air, the rebellious angelic powers and principalities rule this earth for Satan. He is the ruler of the authority of the air. Satan, as the evil spirit, has come into every human being. He operates in every human being without exception. By being such an operator, he has produced a kingdom. Satan now dwells in man’s body.
If you have ever had the experience of casting out demons, you know that the demons like to take the human body as their dwelling place. From his base of operation in the body, Satan will attempt to control the person’s whole being—his mind, emotion, and will. A demon-possessed person is always very much in his mentality. If you can turn him from the prison of his mind to the spirit, the demon, for the most part, will be gone. However, it is difficult to do this. Therefore, you must cast out the demon by the name of the Lord Jesus. After the demon has been driven out, you must help this person turn to his spirit and not to exercise his mentality too much. Otherwise, the demons may return to possess him once more.
(The Kingdom, Chapter 8, by Witness Lee)