The words daemon, dæmon, are Latinized spellings of daimon, Greek "δαιμων", used purposely today to distinguish the daemons of Ancient Greek religion, good or malevolent "supernatural beings between mortals and gods, such as inferior divinities and ghosts of dead heroes" (see Plato's Symposium).

From the Judeo-Christian usage demon is "a malignant spirit that can seduce, afflict, or possess humans." This notion of the daemon as a spiritual being of a lowly order that is largely evil and certainly dangerous has its origin in Plato and his pupil Xenocrates.

However in Hesiod, Phaethon becomes a daimon, de-materialized, but the ills of mankind released by Pandora are 'keres' NOT daimones. Hesiod connects the daimones of the deceased great and good in relating how the men of the "Golden Age were transmuted into Daimones" by the will of Zeus, to serve as ineffable guardians of mortals, whom they might serve by their "benevolence".

In similar ways, the Daimon of a venerated hero or a founder figure, located in one place by the construction of a shrine rather than left unburied to wander, would confer good fortune and protection on those who stopped to offer respect. Thus daemones ("replete with knowledge", "divine power", "fate" or "god") were not necessarily evil.

In Plato's Trial of Socrates, Socrates claimed to have a daimonion, a small daemon, that warned him against mistakes but never told him what to do or coerced him into following it. He claimed that his daemon exhibited greater accuracy than any of the forms of divination practised at the time. The Hellenistic Greeks divided daemons into good and evil categories: Eudaemons (also called Kalodaemons) and Kakodaemons, respectively. Eudaemons resembled the Abrahamic idea of the guardian angel; they watched over mortals to help keep them out of trouble. (Thus eudaemonia, originally the state of having a eudaemon, came to mean "well-being" or "happiness".)

After the time of Plato, in the Hellenistic ruler-cult that began with Alexander himself, it was not the ruler but his guiding daemon that was venerated, for in Hellenistic times, the daimon was external to the man whom it inspired and guided, who was "possessed" by this motivating spirit.

The Greek translation of the Septuagint, made for the Greek-speaking Jews of Alexandria, and the usage of daimon in the New Testament's original Greek text, caused the Greek word to be applied to a "Judeo-Christian spirit by the early 2nd century AD". Then in late antiquity, pagan conceptions and exorcisms, part of the cultural atmosphere, became Christian beliefs and exorcism rituals.

So here we have the Christian forefathers twisting the concept of Daimone into Demon as some kind of evil being to be feared, because of their own fears and superstitions. If only the Alexandria Library still existed.... I'msure that we would have a different view of our history.

In 391, Roman Emperor Theodosius I ordered the destruction of all pagan temples, and Patriarch Theophilus of Alexandria complied with this request. He is also known for making Christianity the official state religion of the Roman Empire. Socrates Scholasticus provided an account of the destruction of the temples in Alexandria in the fifth book of his Historia Ecclesiastica, written around 440.

Daemons were important in Neo-Platonic philosophy. In Platonism daemon here being more in tune with "demigod" rather than an evil spirit. As "Eros" being described as in-between Gods and humankind. In the Christian reception of Platonism, the "eudaemons" were identified with the angels.

It was Cyprian who debunked gods of the pagans as a euhemerist falsehood in his essay, "On the Vanity of Idols". He had this to say of daemons:

“ They are impure and wandering spirits, who, after having been steeped in earthly vices, have departed from their celestial vigour by the contagion of earth, and do not cease, when ruined themselves, to seek the ruin of others; and when degraded themselves, to infuse into others the error of their own degradation. These demons the poets also acknowledge, and Socrates declared that he was instructed and ruled at the will of a demon; and thence the Magi have a power either for mischief or for mockery, of whom, however, the chief Hostanes both says that the form of the true God cannot be seen, and declares that true angels stand round about His throne.

These spirits, therefore, are lurking under the statues and consecrated images: these inspire the breasts of their prophets with their afflatus, animate the fibres of the entrails, direct the flights of birds, rule the lots, give efficiency to oracles, are always mixing up falsehood with truth, for they are both deceived and they deceive; they disturb their life, they disquiet their slumbers; their spirits creeping also into their bodies, secretly terrify their minds, distort their limbs, break their health, excite diseases to force them to worship of themselves, so that when glutted with the steam of the altars and the piles of cattle, they may unloose what they had bound, and so appear to have effected a cure. The only remedy from them is when their own mischief ceases. ”

The daemons are real enough — "the principle is the same, which misleads and deceives, and with tricks which darken the truth, leads away a credulous and foolish rabble" — it is relying upon them that is deceptive. In this way the daemons passed easily into Christian "demons."

The North African Apuleius summed up their character in the Golden Ass (2nd century AD): "The daemones have an animal nature, a rational mind, a soul subject to passions, an aetherial body and they are immortal." The Hellenic and Roman gods were increasingly seen as immovable, untouched by human sorrows and suffering, existing in a perfect heavenly sphere. The Daemones were earthbound, passion-tormented, and in Late Antiquity, loremasters were separating them into the noble kinds and troublemaking kinds. The gnostic (from Greek "gnosis", knowledge) followers of Valentinus (a Roman Exile) multiplied the circles of Daemons and gave them oversight in various areas of concern to people: oracles, animals, and, interestingly, as "patron daemons" of nations or occupations.

en.wikipedia.org/wiki/Daemon_(mythology)

So, really, are Demons evil???

No.