The decisive criterion of the distinction between Islam and hypocrisy (zandaqa)

Returning to his academic role in Nishapur, at the end of 1105, Ghazali is now a spiritual master, strengthened by years of retreat which led him to sharpen his view of things, giving him the ability to distinguish Muslim believers from those who call themselves people of faith.1 This new ability filled him with a fresh goal, as he confesses: “I felt myself able to unravel these ambiguities, as unmasking such people became easier than drinking a glass of water.”2