The Kingdom of God
The Kingdom of Heaven
These are two distinct kingdoms.
One or the other have been on the earth independently before.
They have both been on the earth at the same time before, and will be again.
TheKingdom of Heaven:
The kingdom of Heaven is a physical, literal, visible, touch, see, feel, taste, eat, drink, smell, etc., kingdom. It is the government on the earth where Jesus Christ will rule politically from David's throne in Jerusalem, from the 2nd Advent, forever.
Isaiah 9:6 For unto us a child is born, unto us a son is given: and the government shall be upon his shoulder: and his name shall be called Wonderful, Counselor, The mighty God, The everlasting Father, The Prince of Peace.
Isaiah 9:7 Of the increase of hisgovernment and peace there shall be no end, upon the throne of David, and upon his kingdom, to order it, and to establish it with judgment and with justice from henceforth even for ever. ...
The Kingdom of God
The kingdom of God is a spiritual kingdom. It resides inside the believers by faith, by the Holy Ghost.
It is a Spiritual kingdom. Jesus baptizes us with the Holy Ghost into Body of Christ in the Church Age. The Holy Spirit resides in believers born in future ages.
Romans 14:17 For the kingdom of God is not meat and drink; but righteousness, and peace, and joy in the Holy Ghost.
Eph 3:1 ... I Paul...
Eph 3:2 ... of the dispensation of the grace of God which is given me to you-ward:
Eph 3:3 How that by revelation he made known unto me the mystery...
Eph 3:5 Which in other ages was not made known unto the sons of men, as it is now revealed unto his holy apostles and prophets by the Spirit;
Eph 3:6 That the Gentiles should be fellow heirs, and of the same body, and partakers of his promise in Christ by the gospel:
Eph 3:7 Whereof I was made a minister...
Eph 3:8 Unto me... is this grace given, that I should preach ...
Eph 3:9 And to make all men see what is the fellowship of the mystery, which from the beginning of the world hath been hid in God...
Eph 3:10 To the intent that now... might be known by the church the manifold wisdom of God,
This is the spiritual Kingdom of God in a mystery. It is on the earth now in the spiritual form of the body of Christ. It will be removed from the earth when the church is caught up. Then the tribulation will start, and at the 2nd coming, the Lord will bring back both the Kingdom of God and the Kingdom of Heaven to the earth, and He will be the King of both of these kingdoms. One will be a political kingdom with Jesus ruling from David's throne, the other will be a spiritual kingdom with the Holy Spirit residing in believers.
The important thing to discern is that they are two different kingdoms. But, they have been on the earth at times together, at other times, not at the same time, and that they will both be on the earth together with the same King, Jesus, starting with the 2nd coming.