Insight - Reclusive cleric's followers pose biggest threat to Turkey's Erdogan

Islamic preacher Fethullah Gulen is pictured at his residence in Saylorsburg, Pennsylvania September 26, 2013. Born in Erzurum, eastern Turkey, Gulen built up his reputation as a Muslim preacher with intense sermons that often moved him to tears. From his base in Izmir, he toured Turkey stressing the need to embrace scientific progress, shun radicalism and build bridges to the West and other faiths. The first Gulen school opened in 1982. In the following decades, the movement became a spectacular success, setting up hundreds of schools that turned out generations of capable graduates, who gravitated to influential jobs in the judiciary, police, media, state bureaucracy and private business. Picture taken September 26, 2013. REUTERS/Selahattin Sevi/Zaman Daily via Cihan News Agency

ANKARA/ISTANBUL (Reuters) - At the FEM University Preparation School in Uskudar, a conservative district on the Asian side of Istanbul, young men are quietly receiving specialised coaching in how to pass the exams that give access to the most important jobs in Turkey.

To a casual eye, nothing seems remarkable. As in nearly all Turkish schools, a portrait of modern Turkey's secular founder Mustafa Kemal Ataturk hangs in every classroom. Ataturk's address to youth hangs on the wall at the school's entrance.