fanaticism

noun

1. (countable, uncountable)The characteristic or practice of being a fanatic.

   “The demon of fanaticism was the shape which it took with us; and verily, what with religious republicans, harmonists, quakers, fifth-monarchy men, presbyterians, and the reign of the saints upon earth, it needs the strong hand of a Cromwell to reduce the spiritual chaos to any sort of order.”

   “Witch-hunting became a mania, with all the abuses and excesses which invariably develop with fanaticism.”