Conversation so far:
How did Fethullah Gulen gain fame?
Fethullah Gülen was in the Turkish civil service from his appointment as an assistant imam at Üç Şerefeli Mosque in Edirne.
What was an early notable event related to Fethullah Gulen?
Fethullah Gülen gave his first sermon as a licensed state preacher in 1958, when he was in his teens.

Question: What did his preaching lead to?
Self-contained rewrite: What did Fethullah Gulen's preaching lead to?