"Ah, then, this Kingdom of God may also be called the Kingdom of Heaven! To call, then, the Kingdom of God the Kingdom of Heaven is to ascribe to the Kingdom of God every heavenly and spiritual perfection. The Kingdom of God is, for example, heavenly in its origin—that origin is the bosom of the eternal Father. The Kingdom of God is heavenly in its purpose—that purpose is to restore creation to its original glory. The Kingdom of God is heavenly in its king—that king is the Son of the Highest, Head and body. The Kingdom of God is heavenly in its subjects—those subjects are the children of God. The Kingdom of God is heavenly in its nature—that nature is righteousness and peace and joy in the Holy Spirit. The Kingdom of God is heavenly in its entrance—that gateway is not by birth of blood, nor of the will of the flesh, nor of the will of man, but by birth of God. The Kingdom of God is heavenly in its laws—those laws are not ordinances, rules, or regulations—they are spiritual principles. The Kingdom of God is heavenly in its method—that method is not by might, nor by power, nor by the enticing words of man's wisdom, but by the Spirit of the living God. The Kingdom of God is heavenly in its prerogatives—those prerogatives are for the sons of God to be the salt of the earth, the light of the world, a kingdom of priests after the order of Melchizedek, saviours on mount Zion. The Kingdom of God is heavenly in its privileges—those privileges are to be heirs of God and joint heirs with Christ to the inheritance which is incorruptible, undefiled, and that fadeth not away. In brief, the Kingdom of God is the Kingdom of Heaven—it is the Kingdom of Heaven because it is the kingdom or dominion of the GOD OF HEAVEN!"

https://www.godfire.net/eby/Kingdom1.html