Why is Imam Ghazali (ra) called the ‘proof of Islam’?
Imam Ghazali (rahmatullahi alayhi) is called ‘proof of Islam’ because in the time of his era he was a very high ranked imam and also he contributed significantly to the expansion of Islam. Ghazali wrote more than 70 books on Islamic sciences, Philosophy and Sufism.
He played a major role in Islam and Philosophy and another of Ghazali’s major work is Ihya-ul-Ulum al-Din or Ihya’ul Ulumuddin (The Revival of Religious Sciences). Many excellent remarks were made regarding this book: “If all Islamic sciences were disappeared, they could be taken back from Ihya’ul Ulumuddin.”
Hadhrat Maulana Ashraf Ali Thanwi (rahmatullahi alayhi) relates sayings from many ulama that “If Islam was not haqq (true religion) then Imam Ghazali would not be a muslim”, he further says that if hanafi madhhab was not haqq then Hadhrat Maulana Anwar Shah Kashmiri (rahmatullahi alayhi) would not be a hanafi.
This answer was collected from Tafseer-Raheemi.com the official website of Sheikh Abdul Raheem Limbada (Hafizahullah) of UK.