Source : Webster's Revised Unabridged Dictionary (1913)

Theosophist \The*os"o*phist\, n.
   One addicted to theosophy.

         The theosophist is one who gives you a theory of God,
         or of the works of God, which has not reason, but an
         inspiration of his own, for its basis.   --R. A.
                                                  Vaughan.

Source : WordNet®

theosophist
     n : a believer in theosophy