To be a demon you have to first harm someone. These have never caused harm. But because some faiths are still stuck in the 12th century level of superstition, we fear them only because we do not understand them.
Yet...
You’ve looked to far into the abyss it would seem.
Not quite sure where you get this. Their main mission is to deceive.
I recommend to your reading pleasure Arthur C. Clarke's Childhood's End. Short book, thought-provoking on this topic. Regards.