What's the noun for theosopher? Here's the word you're looking for.
theosophy
(philosophy) any doctrine of religious philosophy and mysticism claiming that knowledge of God can be attained through mysticalinsight and spiritual ecstasy, and that direct communication with the transcendent world is possible.
(religion) Any system which claims to attain communication with God and superior spirits by physical processes.
The system of beliefs and doctrines of the Theosophical Society.
“She speaks admiringly of Madame Blavatsky, theosophy's founder, as well as England's leading theosophists Annie Besant and Charles Leadbeater.”
“Steiner may have broken away from the Theosophical Society, but he did not abandon the eclectic mysticism of the theosophists.”
“To the amazement and disappointment of Annie Besant and some of the other theosophists, he gave up all the power and prestige that he had gained under their tutelage.”