Remember in Genesis 6 where we read that mysterious portion of Scripture about the sons of God who came into the daughters of men? Their prodigy were the Nephilim, mighty men of renown. Then in verse five Moses records that the Lord saw that the wickedness of men on the earth was great? So God commissions Noah to build an ark and save his family and the animals while God floods the earth destroying everyone.
What is that all about?
The Bible tells us that when Satan rebelled and God cast him out of heaven, God cast him to earth. At that time earth was uninhabitual for humans, but for demons, it was a perfect island prison in the cosmos. Satan, was granted some sort of ruling position over the earth, for we know that when he tempted Jesus, he told Jesus he would give him the kingdoms of the world and all their glory if Jesus would just bow down to him. Of course Jesus does not bow down to him.
Also, did you ever notice that in the gospels we see an awful lot of demon possession? Angels only show up occasionally at God's bidding, but Jesus is running into demons everywhere. And He always tells them to be quiet, when they say things like, "What do we have to do with You, Son the Most High?" The legion who got cast into the pigs said this,"Have you come here to torment us before the time?" Luke adds that they begged Him not to send them to the abyss. Where's that? What are they talking about?
I want you to go get your Bible and read these passages: 1 Peter 3:18-22; 2 Peter 2:4-5; and Jude 6.
All of this will come together.