The kingdom of God, the kingdom of heaven, the kingdom of Christ, the kingdom of our Lord is one and the same kingdom. This kingdom is a spiritual kingdom. It means the rule, the authority, the supremacy of Christ, in the hearts of men--those who have entered into it by the new birth.
Let us go to the Gospel of Luke and see how the expression "The kingdom of God" is used; and to the Gospel of Matthew to see that "the kingdom of heaven" is used synonymously. These terms mean the same thing. In the Gospel of Luke, the expression "the kingdom of God" is used in five different ways to show us its full meaning. It is God's kingship; it is His rule or sovereignty, recognized in the hearts and operative in the lives of His people, and effecting their complete salvation. Now watch as this unfolds to us according to the Gospel of Luke.
First, Luke speaks about preaching or proclaiming the kingdom of God. "Christ said unto them, I must preach the kingdom of God to other cities also: for therefore am I sent" (Luk 4:43). "And it came to pass afterward, that Christ went throughout every city and village, preaching and shewing the glad tidings of the kingdom of God" (Luk 8:1; cf. Luk 9:2, 60; 16:16). This truth of preaching the present rule and reign of God in the hearts of men was preaching the gospel as set forth in Mark 1:14, 15 in these words: "And Jesus came into Galilee, preaching the gospel of the kingdom of God, and saying, The time is fulfilled, and the kingdom of God is at hand: repent ye, and believe the gospel."
Our Lord was not preaching that He had come to set up an earthly, material, physical kingdom, but that He had come, commissioned by God the Father, to establish a spiritual kingdom in the hearts of His people, and that this would be accomplished by the gracious gospel of the grace of God toward poor hell-deserving sinners who would repent and believe Him as the King, the Messiah, the One sent down from heaven, the Saviour, God's substitute for sinners.
Second, Luke speaks about entering the kingdom of God. In Luke 18:24, 25 we read, when Jesus saw that the rich young ruler was sad and sorrowful, He said, "How hardly shall they that have riches enter into the kingdom of God? For it is easier for a camel to go through a needle's eye, than for a rich man to enter into the kingdom of God." Listen now as our Lord clarifies this for us! The only way in which we can enter into the kingdom of God is recorded in John 3:3, 5 in these words by our Blessed Lord: "Except a man be born again, he cannot see the kingdom of God...except a man be born of water and of the Spirit, he cannot enter into the kingdom of God." So this rules out any one entering into this kingdom of God except by the new birth, by the direct generating power of the Spirit of God upon the heart, making that individual a new creature and giving him a new heart and nature over which Christ rules as King.
The apostle Paul records: "Now this I say, brethren, that flesh and blood cannot inherit the kingdom of God; neither doth corruption inherit incorruption" (1Co 15:50). This rules out then a fleshly kingdom, a material kingdom of a thousand years here on earth. You see, our friends who claim that there will be an earthly kingdom made up of the Jew after the flesh, and of the nations of the earth who somehow miraculously come through a so-called battle of Armageddon, cannot get around this Scripture, that flesh and blood cannot inherit the kingdom of God.
This same truth is seen here: "Know ye not that the unrighteous shall not inherit the kingdom of God? Be not deceived: neither fornicators nor idolaters, nor adulterers...nor thieves, nor covetous, nor drunkards, nor revilers, nor extortioners, shall inherit the kingdom of God" (1Co 6:9, 10). Again we see that only by the new birth can you enter the kingdom of God, whether you be Jew or Gentile. "And such were some of you: but ye are washed, but ye are sanctified, but ye are justified in the name of the Lord Jesus, and by the Spirit of our God" (1Co 6:11). So we see again that, by the expression, "the kingdom of God," is meant a spiritual kingdom--and only we who are made holy in Christ shall enter into it.
"For this ye know, that no whoremonger, nor unclean person, nor covetous man, who is an idolater, hath any inheritance in the kingdom of Christ and of God" (Eph 5:5). Besides proving again that no unsaved soul is in the kingdom of God, and that it is a spiritual kingdom, we also have written for us very plainly that the kingdom of God and of Christ is the same kingdom. This Scripture should for ever shut the mouths of those who claim that the kingdom of God and the kingdom of Christ are two different kingdoms. No, they are one and the same; call it what you will: the kingdom of heaven, the kingdom of God, the kingdom of Christ, or the kingdom of our Lord; it is a spiritual kingdom.
Thirdly, Luke says about the kingdom of God: "Seek ye the kingdom of God; and all these things shall be added unto you" (Luk 12:31). "Seek ye first the kingdom of God, and his righteousness; and all these things shall be added unto you" (Mat 6:33). Here we are shown the necessity of seeking the kingdom of God. When? "I have heard thee in a time accepted and in the day of salvation have I succoured thee: behold, now is the accepted time; behold, now is the day of salvation" (2Co 6:2). You see, the kingdom of God, His rule over your heart and life in salvation, is to be sought now, because when Christ comes, that ends it all. Then it will be too late, for there will be no second chance. Why? for then the day of judgment will be ushered in (John 5:28, 29).
Let me cry aloud against this teaching that speaks of a chance after Christ comes, a chance for me to be saved in a so-called seven year tribulation period and 1000-year reign of Christ upon the earth. This is false! The Scripture knows nothing about this. The parable of the ten virgins, as well as the rest of the New Testament, teaches that when Christ comes the door will be shut; therefore we are told to watch, for it will be all over. "And while they went to buy, the bridegroom came; and they that were ready went in with him to the marriage: and the door was shut. Afterward came also the other virgins, saying, Lord, Lord, open to us. But he answered and said, Verily I say unto you, I know you not. Watch therefore, for ye know neither the day nor the hour, wherein the Son of man cometh" (Mat 25:10-13).
Fourthly, Luke says the kingdom of God is spiritual; it is within us. "And when Christ was demanded of the Pharisees, when the kingdom of God should come, he answered them and said, The kingdom of God cometh not with observation: neither shall they say, Lo here! or, lo there! for, behold, the kingdom of God is within you" (Luk 17:20, 21). What is the meaning of these verses? The Pharisees and their many followers were looking forward to the arrival of an outward, earthly, visible kingdom, one in which the Jews would occupy a very prominent place. They were hardly able to wait for its arrival. So anxious were they to know when it would be established that they were willing to obtain information from anyone, even Jesus, their enemy.
Our Lord Jesus, however, in His answer told them that they had a misconception concerning the nature of the kingdom, as if it would arrive with loud proclamation, prancing horses, marching armies, parading bands, with "outward show." If that were true, He said, then people would be greeting its arrival by shouting, "Here it is" or "There it is." But our Lord declared that the kingdom, or Lordship, reign or rule of God, is basically spiritual in its essence. It is written inside a person. For you see, wherever God is truly recognized and honored as King, there one finds His kingdom and kingship.
Let me repeat it again: the kingdom of God and His Christ consist of inner qualities such as "righteousness, peace and joy in the Holy Spirit" (Rom 14:17). These qualities exist wherever God is recognized as King. The same mistake is being made today: man is looking for an outward kingdom, but he is just as deceived as the first century Jews. If Christ had intended to set up an earthly kingdom of pomp and splendor, He would have gladly let His followers crown Him king, which they desired to do. But He would not: "When Jesus therefore perceived that they would come and take him by force, to make him a king, he departed again into a mountain himself alone" (John 6:15).
Fifthly, although our Lord Jesus had spoken about His spiritual entrance into hearts and lives, that is, about God's spiritual kingdom or Lordship, He never denies that there will be also a glorious visible manifestation of God's kingdom at His Second Coming, for He speaks of His kingdom as yet in the future: "There shall be weeping and gnashing of teeth, when ye shall see Abraham, and Isaac, and Jacob, and all the prophets, in the kingdom of God, and you yourself thrust out. And they shall come from the east, and from the west, and from the north, and from the south, and shall sit down in the kingdom of God" (Luk 13:28, 29). Also, "Fear not, little flock: for it is your Father's good pleasure to give you the kingdom" (Luk 12:32).
Yes, there shall be a manifestation of this glorious kingdom when the Lord Jesus Christ shall deliver up the kingdom to the Father (1Co 15:24) and confess our names before Him in heaven; and we shall be in that eternal state of happiness and bliss with our new bodies made in the likeness of our Blessed Lord who bought us with the price of His own precious blood. Therefore, we look not for a partial restoration of this earth in a 1000-year earthly reign of our Lord, but for the complete restoration of all things in the eternal state in the new heaven and the new earth. "Nevertheless we, according to his promise, look for new heavens and a new earth, wherein dwelleth righteousness" (2Pe 3:13).