OK.
What kind of bothers me about this, if we're not wrestling against flesh and blood, I would wonder why we'd be expecting a non-spiritual, non-new-creational kingdom of Christ over the unsaved in return. It would seem to me only a flesh & blood authority over the unsaved, without spiritual condemnation and judgment.
Well, it appears that those who go to the New Jerusalem do not return until the millenium is over (Rev3 & Rev 21). There is some kind of governing authority of Christ during the millenium and we are reigning with Him. It has been suggested that since we will be like the angels, we will visit the earth just as they do. I am looking forward to seeing how it's all going to work out. As far as what it's going to be like on the earth, scripture says that 10 men will take hold of one Jew and go with him. It seems that people will know who God is and that Israel will be the established authority over all nations at that time.
Zec 8:23Thus saith the LORD of hosts; In those days [it shall come to pass], that ten men shall take hold out of all languages of the nations, even shall take hold of the skirt of him that is a Jew, saying, We will go with you: for we have heard [that] God [is] with you.
Isa 2:3And many people shall go and say, Come ye, and let us go up to the mountain of the LORD, to the house of the God of Jacob; and he will teach us of his ways, and we will walk in his paths: for out of Zion shall go forth the law, and the word of the LORD from Jerusalem.
Isa 66:10¶Rejoice ye with Jerusalem, and be glad with her, all ye that love her: rejoice for joy with her, all ye that mourn for her:
Isa 66:11That ye may suck, and be satisfied with the breasts of her consolations; that ye may milk out, and be delighted with the abundance of her glory.
Isa 66:12¶For thus saith the LORD, Behold, I will extend peace to her like a river, and the glory of the Gentiles like a flowing stream: then shall ye suck, ye shall be borne upon [her] sides, and be dandled upon [her] knees.
Isa 66:13As one whom his mother comforteth, so will I comfort you; and ye shall be comforted in Jerusalem.
I don't think I need to work with levels of heaven here. Earth is not a level of heaven as far as I know. The Devil was here for the birth of the man-child who rules with a rod of iron. So the Devil's cast awhile ago. At least that's what it comes down to with me & Rev 12.
Maybe I'm trying to explain something that I don't have a complete grasp on myself. There is a lack of info on the subject in the canon of scripture. I think that Enoch 1 has some info on it which was once a part of scripture and is often quoted in scripture.
I should say that it is my understanding that the devil was kicked out of the high heavens before humans were created. There are angels who lost their place in heaven because of coming down and creating the Nephilim with human women. They are locked up in "gloomy dungeons" awaiting judgment according to Peter and Jude (and Enoch). But I don't know if those angels have anything to do with the angels that fell with satan...I'd think not because of the different timing.
Enoch describes, if I recall correctly, a spiritual place or mountains where the devil has his kingdom in the air currently. To us, I would think that would still be "in the heavens". They have power to influence people of the earth and are given that power by spiritual laws (remember, don't give the devil a foothold...when we do something that is inappropriate or "unlawful" in God's sight, we give the devil a "legal" reason to wreak havoc in our lives). Now, when the devil is finally cast all the way down to the earth with his "pals" (1/3 of the angels), then things are really going to get messy here. We are told that he will give his power to the beast and will reign for 42 months. He intends to set up his kingdom and mislead as many humans as possible with the mindset, 'if I go down, I'm taking as many humans with me as possible'.
The church (body of believers infilled with the Holy Spirit) is what restrains the devil on earth through the power of the Holy Spirit and in the name of Jesus and Michael is what restrains the devil in heaven. Once the church is removed from the earth, there is no one here to restrain the devil. Michael fights the devil in the heavens and kicks the beast and friends down to the earth where the devil then can build his "kingdom" for a 42 months before he is bound for a day(millenium), released for a short time, and then destroyed in the lake of fire.
We also know from scripture that good angels and bad angels war with each other in the heavens. Usually when that is happening, wars break out on earth. Daniel talks about the prince of Greece, and the prince of Persia, etc.
It kind of makes me feel like humans are just puppets in a twisted puppet show.
So, that's my understanding of it all at this moment. There are some here who may be able to explain better or who have more insight than I.