I think I know this person – kidding! I found this humorous aside in Stephen Holmes’ article on the Trinity in Gundry & Sexton (eds), Two Views on the Doctrine of the Trinity (Counterpoints: Bible and Theology; Zondervan. Kindle Edition), 48; p. 28 in the print edition. Holmes is discussing the changing character of words. In the eighteenth century, when the plaque was supposedly written, enthusiast meant fanatic.