The Kingdom of the heavens is not the Kingdom of God. It is the Kingdom of the heavens! The kingdom of the angels in the heavens from Adam's sin onwards. The Lord's prayer says:
Thy will be done on earth as it is in heaven (Matthew 6).
So the heavens had God as their king at the time of Jesus' ministry and were doing the will of God. They had Satan as their king before he fell when he induced Adam to sin. The Kingdom of the heavens had drawn near to man at the time of Jesus' ministry because he was about to die and ransom Adam angelically on 33Nisan16, which would enable human saints to be resurrected into the Kingdom of the heavens as angels. Mankind was almost ready to join the kingdom of their heavenly brothers. The point is that the Kingdom of the heavens of Matthew is not another name for the Kingdom of God. This is really important because nearly all churches think that the two are the same and therefore deduce that the Kingdom of God is in the heavens. It is not. It is down here on the earth but run with a different heavenly administration to the one Satan ran from 3990Iyyar17 (first fruits after 3990Iyyar14, when Adam was passed over from Michael to Satan in the greater bowl of soup deal) to 2011Iyyar14 and then for a further 1266 days of the miracle ministry payback from 2011Iyyar14 to 2014Heshvan20 and then the heavenly war of Revelation12 starting when Michael stood up fulfilling Daniel12 on 2014Chislev13, and then some kind of heavenly Passover of Satan and the dragon (on 2015Ab14), then his eviction down the 30 steps of Jacob's ladder, from 2016Heshvan20 to 2016Chislev20, and then the final 42 months of authority given to the dragon and given by the dragon to the wild beast over Adam from 2017Ab17 to 2020Shebat14, the Babylonian Abrahamic Passover, the end of the world officially, the end of the divine authority for the world. Then the Kingdom of God is appointed on 2020Shebat16, when Jesus is appointed as Caesar to Adam.
A notable exception to normal kingdom nomenclature in Mark is...
10 Blessed is the coming kingdom of our father David! Save, we pray, in the heights above! (Mark 11).
This is the Kingdom that recommenced at the end of the Gentile Times. For Russell sat upon the throne of David, ruling over the sons of Isaac, through the ICC and the sons of Jacob through the JAC from 1914Tishri onwards. Russell must have had some Jewish ancestry somewhere! Or if not then his last successor has.
A notable exception to the normal kingdom nomenclature in Matthew is...
29 But I tell you, I will by no means drink henceforth any of this product of the vine until that day when I drink it new with you in the kingdom of my Father (Matthew 26).
This could not have said: The Kingdom of the heavens, because angels cannot drink wine. The kingdom of my father is the kingdom of God. Paul explains that Jesus is a vassal king of God during the first part of the 1,000 years, then he hands the Kingdom over to his God and father...
22 For just as in Adam all are dying, so also in the
Christ all will be made alive.
23 But each one in his own rank: Christ the first fruits, afterward those who belong to the Christ during his presence.
24 Next, the end, when he hands over the kingdom to his God and Father, when he has brought to nothing all government and all authority and power.
25 For he must rule as king until [God] has put all enemies under his feet.
26 As the last enemy, death is to be brought to nothing [on 2021Tishri21, the end of entry into the 1st death or on 2021Tishri16, the resurrection of the late partaking OMCs].
27 For [God] subjected all things under his feet. But when he says that 'all things have been subjected,' it is evident that it is with the exception of the one who subjected all things to him.
28 But when all things will have been subjected to him, then the Son himself will also subject himself to the One who subjected all things to him, that God may be all things to everyone [For it is God's Kingdom] (1 Corinthians 15 NWT)
Eventually all death including even the second death - Hell - will be brought to nothing
So the old JW idea that people who go to Hell are finished permanently is plainly wrong, since even the second death is to be brought to nothing. Likewise we read...
4 And he will wipe out every tear from their eyes [this does not mean there will be no tears. It means all tears will be wiped. People will be there to help anyone in distress. If there is an injustice it will be dealt with. If there is a death, there will be a resurrection. If there is an illness, there will be a cure], and death will be no more [neither the first death at the start of the kingdom nor the second sometime after the end of the kingdom], neither will mourning nor outcry nor pain be anymore. The former things have passed away (Revelation 21).
For more on the end of Gehenna see I14.