Cleric, political activist or peaceful reformer, who is Fatehullah Gulen?

WION New Delhi, Delhi, India Dec 22, 2016, 11.41 AM (IST)
Cleric Fatehullah Gulen lives in virtual seclusion in Pennsylvania, in the United Sates. But he's accused of inspiring people in Turkey to overthrow President Erdogan. What's the truth about Fethullah Gulen?