F.F. Bruce, the noted Scottish-born biblical scholar, wrote in Acts of the Apostles (1990, p. 102), commenting on chapter 1, verse 6:
“This hope of an earthly and national kingdom (cf. Mk. 10:35-37; Lk. 1:68-75) was recast after Pentecost as the proclamation of the spiritual kingdom of God, to be entered through repentance and faith in Christ.”
In other words, the Kingdom is redefined from the future world rule of God through the Messiah into a spiritual rule by your church or in your heart. That view has become standard in Christianity, and from it was born the popular saying, “Already Not Yet,” a formula used to promote “realized eschatology.” But this was not unique to Bruce or any other scholar.
The idea that the Kingdom was inaugurated by Jesus and is now present was first developed and spread by the so-called Church Fathers, such as Irenaeus, who framed the Kingdom in terms of salvation history. Others, like Clement, recast it as a wholly spiritualized ethical and moral reality, while Origen internalized it as autobasileia — the “kingdom within.” Hence, under Constantine, the church fused Kingdom language with empire: “one God, one Logos, one Emperor, one Empire.”
However, in sharp contrast stands the Bible’s definition of the Kingdom of God.
The prophets describe a real future world order: Daniel 2 and 7 speak of the overthrow of human empires, with the Son of Man and the saints of the Most High God receiving the kingdom; Psalm 2 speaks of God’s Son ruling the redeemed nations; Isaiah 19, Zechariah 14, and Isaiah 65-66 give a vision of a restored earth and renewed creation. The New Testament did not change these seminal visions about “the day of the LORD,” Yahweh God.
The Kingdom was Jesus’ purpose-driven life (Luke 4:43). He announced, among matters of first importance, that the Kingdom was “at hand” (Mark 1:14-15) “near,” not yet here. As a result, he taught his disciples to pray, “May Your kingdom come” (Matt. 6:10), and spoke of it consistently as future:
“Amen! You who have followed me, when the world is reborn and the Son of Man will sit on his throne of glory, you too will sit on twelve thrones, governing the twelve tribes of Israel. And everyone who has left their homes, brothers, sisters, father, mother, children, or properties, because of me, will receive back a hundred times more, and will inherit the life of the age to come.” (Matt. 19:28-29)
“I tell you that I will not drink of the fruit of the vine from now on until the Kingdom of God comes.” (Luke 22:18)
These represent only a few of the direct sayings of Jesus that place at the heart of the Christian Gospel a predominantly future Kingdom, which will begin only at his Parousia. Hence, after Jesus’ death, Joseph of Arimathea was still “waiting for the kingdom of God” (Mark 15:43; Luke 23:51), and the apostles rightly asked, “Are you restoring the kingdom to Israel?” (Acts 1:6). That is why Paul is right later to admonish the church at Corinth:
“You are already filled. You have already become rich. You have begun to reign as kings without us! I wish indeed that you were really reigning as kings, so we would also be reigning as kings with you!” (1 Cor. 4:8)
Likewise, he warns Timothy:
“This instruction I entrust to you, Timothy, in keeping with the prophecies previously made concerning you, so that by them you may fight the good fight, keeping faith and a good conscience, which some have rejected and suffered shipwreck in regard to their faith. Among these are Hymenaeus and Alexander, whom I have handed over to Satan, so that they will be taught not to blaspheme.” (1 Tim. 1:18-20)
And again Paul mentions one of these men and describes his message as spreading "like gangrene" because such people "have gone astray from the truth by saying that the resurrection has already taken place, and they overthrow the faith of some.” (2 Tim. 2:17-18)
These strong warnings alone should destroy other theories about the Kingdom, such as Preterism, Amillennialism, or Postmillennialism.
At the same time, sometimes the word “kingdom” is used in abstract ways for royal authority or kingship (Luke 19:12, 15; 23:42; John 18:36), or for something to receive (Mark 10:15), seek (Matt. 6:33; Luke 12:31), or strive for (Matt. 11:11; Luke 16:16; Matt. 21:31; 23:13; cf. Luke 11:52; 1 Thess. 2:12; Rev. 1:6). Some of these sayings reflect what I call standard prophetic language for a future event so certain that it can at times be spoken of as past or even present (e.g., Matt. 12:28; Luke 11:20). But this should not alter the meaning of the Kingdom. Also note the mistranslation “within you” in Luke 17:21.
The Kingdom is established strictly in the future, when God, through His Son, will restore the Davidic throne in the new Zion/Jerusalem, leading to the restoration of all things. Then “the saints of the Most High will receive the kingdom and will possess the kingdom forever, and ever,” and “the kingdom, the dominion, and the greatness of all the kingdoms under the whole heaven [will] be given to the people of the saints of the Most High. Their kingdom will be an everlasting kingdom, and all dominions will serve and obey them” (Dan. 7:18, 27).
To redefine that Kingdom as mainly spiritual or ecclesiastical is to forsake everything the prophets, Jesus, and his apostles taught and died for. In effect, it is “to preach a different Gospel from the one we preached to you” (Gal. 1:8).