The Gospel of the Kingdom, in it's essential, is that the "other kingdom" will be destroyed.
We can look at the kingdoms of men, and see, only passing flesh kingdoms.
There is however another kingdom that has operated on the earth, and in flesh, from day one, and that is this one:
Matthew 12:26
And if Satan cast out
Satan, he is divided against himself; how shall then
his kingdom stand?
Where we read of Kingdom rising against kingdom (little k kingdom for Satan's) these are the Kingdom/kingdom(s) being spoken of.
And beyond this, there is much more to observe, for example, we know for no uncertain fact "how" the little k kingdom receives it's power, how it operates, how it functions, directly out of the N.T., here for example:
1 John 3:8
He that committeth
sin is of the devil; for the devil sinneth from the beginning.
For this purpose the Son of God was manifested, that he might destroy the works of the devil.
God in Christ specifically directed His sights to the other kingdom, and it's occupants. Jesus also shows us many many things about how these entities, unseen, operate.
In Mark 4:15 for example, we can see that where the Word is sown, Satan enters the heart to blind/steal Word. A sin, of course. And not of the person, but of Satan. This is a "real" and "dynamic" principle. There is no avoiding this encounter for any "flesh man." All have sin, and the scripture has concluded all under sin. Gal. 3:22.
The overlap between man and Satan in the flesh can't be made any clearer. But, it's a testimony to the other kingdom, that it isn't seen or perceived by believers. Pity, eh?
How then is this kingdom "empowered?"
Here, Paul shows us where sin derives it's power. It's the power of "resistance" that Satan has been given.
1 Corinthians 15:56
The sting of death is sin; and
the strength of sin is the law.
Paul lays this same principle on himself, here in Romans 7:7-8
7 What shall we say then? Is the law sin? God forbid. Nay, I had not known sin, but by the law: for I had not known lust, except the law had said, Thou shalt not covet.
8 But
sin, taking occasion by the commandment, wrought in me all manner of concupiscence. For without the law sin was dead.
This is one of the Spiritual reasons we don't put our "flesh" under the Law, because it does have the power to cause a very adverse reaction by the other party. We even know what those reactions are. Lying. Hypocrisy. 1 Tim. 4:2. And ultimately such "victims" end up wanting to see other christians burned alive forever or eternally killed. This "internal infection" has thoroughly permeated ALL the churches in their various divisions. All you have to do is ask them what happens to the "other denominations." Their anti-fruit is seared into their brains, and more than likely they WON'T be coming out from under the iniquity ether of the other kingdom, at least while they are still in the flesh.
Paul even advises us on the "end game" with this exercise, here, again, from Romans 7:13, in part:
"But sin, that it might appear sin, working death in me by that which is good;
that sin by the commandment might become exceeding sinful."
So, there we have our basic scriptural spiritual vs. the anti-Christ spirit dynamic, between these TWO kingdoms, one of which remains to come to the forefront.
and btw, fwiw, the most obvious sign of the operation of the little k, kingdom heads, is the blaming and accusations to believers. This IS one of the hallmarks, and the most easily recognized SIGN of their internal impositions. They'll force "believers" to see anyone but THEM. Another sign is the inability to speak truthfully about them, in the internal actions of the "victims." They just can't speak the truth. It's against what 'they' do.
The Gospel of Thee Kingdom, is that the other kingdom will be utterly destroyed. And, seeing the "locale" of that kingdom, uh, yeah, it will be more than a little uncomfortable for the current usurpers.