[Hebrews 11:6]

Demons (i.e., fallen angels) frequently and freely enter our world for their own demented reasons, usually for enticing fools into spiritual bondage.

For the definitive study of this issue, please see

Lights In the Sky and Little Green Men:
A Rational Christian Look at UFOs and Extraterrestrials.

[Jamestown1630]

Sorry; that’s not logical to me. I believe that God is One, just like the Bible says, Belief in the kind of dualism that juxtaposes God and a devil may as well be a kind of ‘demon’ itself, in mens minds.

Vermont Lt is correct in post 30 - humans don’t need supernatural help to screw up. Their unwholesome imaginations do that job just fine.