demonism

/D IH0 M AA1 N IH0 Z AH0 M/
noun
  1. 1

    Belief in, or worship of demons or devils.

  2. 2

    The quality of being demonic (often figuratively).

  3. 3

    An act or event attributed to demons or devils; an evil act.

Source: https://en.wiktionary.org/wiki/demonism