Al-Ghazali

Abū Ḥāmid Muḥammad ibn Muḥammad al-Ghazālī (1058-1111) (), often Algazel in English, was born and died in Tus, in the Khorasan province of Persia. He was an Islamic theologian, jurist, philosopher, cosmologist, psychologist and mystic of Persian origin, and remains one of the most celebrated scholars in the history of Sunni Islamic thought. 
He is considered to be a pioneer of the methods of doubt and skepticism, and in one of his major works, "The Incoherence of the Philosophers", he changed the course of early Islamic philosophy. He changed the early Islamic philosophy away from an Islamic metaphysics influenced by ancient Greek and Hellenistic philosophy. The new way was towards an Islamic philosophy based on cause-and-effect that was determined by God or intermediate angels, a theory now known as occasionalism.
Ghazali has sometimes been celebrated in both the East and the West as the greatest Muslim after Muhammad.