Demons are much like Angels in that they are lesser beings who are usually under the authority of the prevailing Devil. They are always malevolent in nature, and seek to torment humans with their dark and wicked ways. The means by which they wreak havoc are threefold:
#1: In spiritual form they whisper evil thoughts into a person's mind, trying to corrupt them to do wrong.
#2: In spiritual form they restlessly wander the earth and torment others with their mere appearance.
#3: They actually possess someone and control their actions, usually causing them to harm others, or at the very least, themselves. This is called 'Possession', and even today it wreaks fear in many just by even mentioning it.
Another thing that is usually representative of demons in nearly every culture; they are usually grotesque in appearance, and more than likely half animal at least.
Perhaps one of the greater influences in restoring interest in demons and their study in the mid-20th century was Anton LaVey, the author of the Satanic Bible and the founder of the Church of Satan. LaVey believed that Christianity was a repressed religion, and the true power of Satanic belief was the lack of limits imposed on the believer. LaVey believed that man ought to have the supreme choice over his life, not a God, or any god.
Damned by the gods; feared by man; demons have made their home on earth, and they're here to stay.
