The Outlined Copy of Ihia'a Ulum Al-deen (Reviving the Sciences of Religion)

Imam Abu Hamid Muhammad ibn Muhammad al-Ghazali — known across the Muslim world as Hujjat al-Islam, the 'Proof of Islam' — was an eleventh-century theologian, jurist, philosopher, and Sufi master whose works shaped the subsequent thousand years of Sunni religious life more profoundly than any other writer outside the Companions and the early imams. Born in 450 AH / 1058 CE in the city of Tus in Khurasan (modern northeastern Iran), he was orphaned young and educated under the guardianship of a Sufi friend of his father's. He went on to study under the leading Ash'ari theologian al-Juwayni, and at thirty-three was appointed by the Seljuq vizier Nizam al-Mulk to the prestigious chair of the Nizamiyya College in Baghdad — among the highest scholarly positions in the Islamic world.

At the height of his fame, al-Ghazali underwent a profound spiritual crisis, abandoned his teaching post, distributed his wealth, and spent eleven years wandering in solitary retreat through Damascus, Jerusalem, Hebron, Mecca, and Madinah. From this period of withdrawal emerged his magnum opus, Ihya' 'Ulum al-Din ('The Revival of the Religious Sciences'), a forty-book synthesis of fiqh, theology, and Sufi ethics that remains the most influential work of Islamic spirituality ever written. His other major works include Tahafut al-Falasifa, his celebrated critique of Aristotelian-Avicennan philosophy; al-Munqidh min al-Dalal, his spiritual autobiography; al-Mustasfa fi 'Ilm al-Usul on legal theory; and Bidayat al-Hidaya on the beginning of the spiritual path.

Al-Ghazali returned briefly to teaching at the Nizamiyya in Naysabur before retiring to a small ribat in his birthplace of Tus, where he died in 505 AH / 1111 CE. His integration of legal scholarship, theological precision, philosophical sophistication, and lived Sufi spirituality became the defining template for Sunni religious learning across regions, languages, and centuries — a legacy reflected in his enduring title across the Muslim world: Hujjat al-Islam.