The phrase “kingdom of heaven” is only found in the book of Matthew, though it is described all throughout the scriptures to Israel.
Luke uses the phrase “kingdom of God” the most. He uses it primarily to describe Israel’s promised kingdom, but sometimes in Acts referring to what Paul taught.
Paul uses the phrase “kingdom of God” eight times in his epistles and never once uses it to describe the earthly kingdom to Israel.
More Kingdoms …
There are more kingdom phrases than just “kingdom of heaven” and “kingdom of God”. Paul uses the phrases “kingdom of his dear Son”, “kingdom of Christ”, and “heavenly kingdom” which are not found anywhere else in the Bible.
They are strictly Pauline because the main subject of the revelation given to Paul was not about the earthly kingdom discussed in Matthew or Luke. Neither was it about Israel and the fulfillment of their scriptures.
It was a mystery of Christ about those who would sit in heavenly places.
“Whereby, when ye read, ye may understand my knowledge in the mystery of Christ” – Eph 3:4
In this mystery was defined a new creature called the Church, which is his body.
“And hath put all things under his feet, and gave him to be the head over all things to the church, Which is his body, the fulness of him that filleth all in all.” – Eph 1:22-23
The Church and Kingdom are Different
The church is not a kingdom or a nation. Being seated in heavenly places is not the kingdom of heaven come to earth (Eph 2:6, Mat 6:10).
People will enter into the kingdom. This language is not used when talking about the Church.
The kingdom is a dominion; the Church is a body.
The kingdom is the subject of prophesy; the Church is not.
The kingdom will be on earth; the Church is forever in heaven.
The kingdom has gates, walls, and mansions. The Church is a spiritual union without the rudiments of the world (Col 2:10, 20).
Same Phrase, Different Meanings
The phrase “kingdom of God” is used by Matthew, Luke, and Paul.
In Matthew we learn the “kingdom of God” can refer to the physical, literal, earthly kingdom promised to Israel.
In Luke we learn it can also speak to the spiritual principles in that kingdom.
With Paul we learn it can also refer to the universal spiritual reign of God which includes all dominions and principalities.
What does this mean? That the same phrase, “kingdom of God” or “kingdom” can have different uses and different meanings, in different contexts.
For this reason, Paul says we have been translated into the kingdom of his dear Son placing the Church also under the universal dominion of Christ (Col 1:13-18). Being in Christ we are under God’s rule (1 Cor 10:3).
All Things in Christ
Everyone in Christ will be under God’s authority in his eternal reign according to Ephesians 1:10. Some will be on earth, some will be in heaven.
“That in the dispensation of the fulness of times he might gather together in one all things in Christ, both which are in heaven, and which are on earth; even in him:” – Eph 1:10
The Church will be in heaven having nothing to do with the earth and the things to come here. The kingdom is never the same as the Church.
People struggle with the difference between the “kingdom of heaven” and the “kingdom of God” in the Bible. The answer is in the context of what was prophesied and what was a mystery. If you do not rightly divide, you will get it wrong.
It would be better to find the dividing line between prophecy and mystery than to force a separation between two kingdom phrases used in Jesus’ earthly ministry that may not be as clear as some dispensationalists would like.