The idea is that the Biblical people didn't have our frame of reference. They might have called ET's angles/demons/Ophanim/Seraphim/Cherubim/etc.
The "powers and principalities" that we wrestle against are actually orders of angels in the Angelic Hierarchy but people tend to think it meant the Devil/Evil.
Satan is just the concept of the propensity of evil within humans. But it's been corrupted into a being of punishment and torment that resides in Hell. But all that is from pagan Greece and Rome.
If you read Enoch, you'll notice he's taken aboard a vessel and shown space where he witnesses a blackhole, but because of his frame of reference he describes it as a place where souls are destroyed/punished.
I know that most Christians want to believe that the whole aliens phenomenon is the fallen angels messing with us, but those "angels" were either captured and contained within the earth or destroyed in the blackhole that Enoch witnesses.
The reason Enoch and the other Apocryphal texts were removed is because they give too much knowledge. And the priest class of the day wanted to limit/control people. So they corrupted the Word with pagan ideologies to increase their number of tithes as well as control as many citizens as they could.
I probably sound crazy now, but if you give it a bit of research into the Apocrypha, Hebrew tradition/language, and the translation processes for yourself, you'll see it. :l