Does the Bible say anything about what demons *are*?

As I have answered here, I will repost it.

There were plenty of references of demons in the Bible if you look close enough. In Matt 8 verse 28 through 32, he heals two demon possessed men. In here, the demons begged Jesus and asked him if he came here to torture them before the appointed time.

What would that mean? Demons are not angels who have followed Lucifer when he turned against God. These demons are souls of people who did not believe in God. They are the reasons for all kinds of sickness and disabilities. In the appointed time, they will be condemned for their actions when they lived.

The back up of this explanation is on Matt 12 verse 24. Here, Pharisees said that Jesus drives out demons with the power of the prince of demons. Note the word, drive out. Edit: Jesus has contridicted the Pharisees when they said that he was using the power of Devil.

Some of you will say that the bible verse I have used only proves that there are demons. However, there is no reference in the bible as far as I can see that says that angels can control a person.

No where in in scripture does it state fallen angels are demons, evil spirits. Although the possibility of them being human souls is also rejected due to biblical clarification of the dead being held in various places, or the general reference to Sheol. There is an account where God permits the prophet Samuel to return from the dead, make what you will from that, as it seems to explain that he was "brought up" and "disturbed". We know at least with Christians it's explained explicitly that to be absent from the body is to be present with the Lord. Jesus himself stated to the insurrectionist on the cross, that today you will be with me in paradise. There is the parable of Lazarus and the rich man, which give us an insight into the afterlife, mentioning both the bosom of Abraham and hell or hades, though as a parable I'm not certain of it's accuracy based on reality.

There is a theory that unclean spirits are the remaining souls of the Nephilim that died in the flood, being hybrid creatures of human and angelic offspring their spirits are left to roam this earth until judgement day. This proposition is clarified from the Book of Enoch, though it is not canonical it is quoted twice in scripture, here and here, those passages referring to the angels, not who fell in the heavenly war, but the ones that willingly left to mate with women revealed in Genesis 6:1-4, these specific angels are chained and held till judgement day.

I think most just assume fallen angels are demons, though this is never explicitly stated. There could just as easily be both, working under satan. It may be left biblically ambiguous for the mere fact that it is not important we know the exact ontology of demons, only that we are aware of what they are capable of.

Fr. John A. Hardon, S.J.'s article What are Possession and Obsession by the Devil?, implies the thesis that demons are human unbelieving souls is false in writing:

We have been reflecting mainly on the angels, as such, and have seen something of what happened at the dawn of angelic creation. Some of the angelic hosts remain faithful to God. Others rebelled against the Creator and became demons.

We have also seen that the angels are not just in a world by themselves. The faithful spirits are angels precisely because they are messengers of God to guide our minds and direct our wills towards that heavenly destiny for which we are made. The rebellious spirits have been allowed, from the dawn of human history to tempt human beings away from their loyalty to God and thus lead men into sin.

In Matt 8:28-32 (compare Mk 5:1-20), the cure of the demoniacs, there is no reason to presume the demons are human souls. This reading of the passage is not in the passage, but an errant interpretation. In v29, The New Jerome Biblical Commentary states (p694, 42:59):

before the right time: This Matthean gloss reflects the intertestamental idea that the demons were free to trouble humanity until the end time (1 Enoch 15-16; Jub. 10:8-9; T. Levi 18:12)

In Matt 12:24, the Pharisees claim Jesus drives our devils through the price of devils. Jesus links his exorcisms to those of the Jewish exorcists. Jesus is clearly claiming his (and the Jewish exorcists) power is from God. This passage once again does not address the claim that devils are the souls of human beings who do not believe in God.

In Matt 25:41. Then he shall say to them also that shall be on his left hand: Depart from me, you cursed, into everlasting fire, which was prepared for the devil and his angels.

In the context of this passage, referring to men who are not permitted into paradise because they did not show concrete love to their fellow men, it contrasts two different beings, human and demonic & implies man as separate and distinct from the devil and his angels.