Why are we afraid of ghosts/spirits?

[thatkidakayoungguy]

People tend to be scared of the supernatural, especially in the cases of so called ghosts. In the bible we see that spirits sometimes scare people in their true form. In the case of what people call ghosts, is it bc of a subconscious acknowledgement of evil deception or something else? The bible also says not to conjure up the dead, or to practice witchcraft, which can involve ghosts, fyi.

[Aestatis]

Anything that people don't know is scary. Anything that can't be explained is scary. Hence ghosts, and supernatural stuff is scary. Even from a religious view, the fact that a ghost/demon could appear and just do whatever is scary, since most ghost stories don't tend to be good and all that.