What I learned was the etymology of the term (it makes so much sense!):
c.1600, from M.Fr. enthousiasme, from Gk. enthousiasmos, from enthousiazein "be inspired," from entheos "inspired, possessed by a god," from en- "in" + theos "god" (see Thea). Acquired a derogatory sense of "excessive religious emotion" (1650s) under the Puritans; generalized sense of "fervor, zeal" (the main modern sense) is first recorded 1716.
Happy to say, contemporary Unitarianism is much friendlier to the idea of Enthusiasm. I consider myself an enthusiast by temperament: possessed by a god. I mean, I understand--theoretically--the complaint against the enthusiasts. Charles Chauncey's cautionary work, gathered together under the title, Enthusiasm Described, and Cautioned Against, would be right at home in contemporary academia, which looks skeptically at notions of divine and supernatural light. So much the safer for academia.
But... I wonder if I could publish here and get academic credit--