There are two kingdoms; the kingdom of this world, and the kingdom of God. A proper understanding of this concept is vital to our Christian walk, as it effects how we live and act in every area of our lives.
First, there is the world. This is where mankind lives. From the beginning of creation, man has inhabited the globe. It is divided into continents and nations, kingdoms and dominions, where men of every tribe and tongue dwell. We all spend our lives in this world, from the day we are born, until the day we die.
This is the world that God created (Gen 1:1). We read that God has made of one blood all nations of men for to dwell on all the face of the earth, and hath determined the times before appointed, and the bounds of their habitation (Acts 17:26 KJV).
However, sin has marred this world. We see corruption and evil everywhere. What God created as good (Gen 1:31), was corrupted by the fall, and given over to the dominion of the devil.
And the devil, taking him up into a high mountain, shewed unto him all the kingdoms of the world in a moment of time. And the devil said unto him, All this power I will give thee, and the glory of them: for that is delivered unto me; and to whomsoever I will I give it. And if thou therefore wilt worship me, all shall be thine. Luke 4:5-7 KJV
The bible declares that this world is under the dominion of Satan, the god of this world (2 Cor 4:4). In John 12:31, he is called the prince of this world. (see also John 14:30, 16:11).
Wherein in time past ye walked according to the course of this world, according to the prince of the power of the air, the spirit that now worketh in the children of disobedience. Eph 2:2 KJV.
This world is evil (Gal 1:4). Under the rule of Satan, the whole world lieth in wickedness (1 John 5:19). All of the wickedness that prevails in the world today, can be traced to the activity of Satan in this world, as he entices men to yield to his control.
Then we have the kingdom of heaven, also referred to as the kingdom of God. This kingdom is under the rule of Jesus Christ, and is filled with those who have committed their lives to follow Him. Unlike the kingdom of this world, where men are born physically into it, the kingdom of heaven can only be entered by the new birth (John 3:3,5). It is a spiritual kingdom that exists within this physical world we live in, yet separate from it. Those who have entered this kingdom as disciples of Jesus, live by the law of love. They love God with all of their heart, soul, and mind, and their neighbor as themselves ( Matt 22:37-40). They treat others in the same way that they would be treated (Matt 7:12).
The kingdom of heaven is made up of individuals who have renounced all for Christ (Luke 14:33). As Lord and King, Jesus is to be obeyed. Those who love Him, will keep His commandments (John 14:21). This kingdom is the opposite of the world. The world’s system is that of selfishness, while Christ’s kingdom is based upon sacrificial love,
This is my commandment, That ye love one another, as I have loved you. Greater love hath no man than this, that a man lay down his life for his friends. John 15:12-13 KJV.
Those who have entered the kingdom of God still live in this physical world, they are inhabitants of cities and countries, but their allegiance is now to Christ. They live as strangers and aliens (Heb 11:13). Jesus teaches us that as Christians, we are in, but not of, the world (John 17:9-16). This has great ramifications for us; it affects every area of our lives.
It is like an individual going to another country on business. He is in this country for an extended period of time. He is living in a foreign country, but not as a citizen. He does not participate in its politics, or get entangled in its affairs, because he is only there on business, and cannot let anything get in the way of that business. In the same way, the citizens of God’s kingdom are here in this world as ambassadors of Christ (2 Cor 5:20). They do not get entangled in the affairs of this world (2 Tim 2:4), because they are called upon to make the business of the heavenly kingdom their priority (Matt 6:33).