St. John Damascene (Bishop and Doctor of the Church), discusses his debates with Muslims and exposes the teachings of their false prophet, Muhammad. He shows that Muslims do not worship the same God as Catholics. The following passage is taken from Saint John’s monumental work, the Fount of Knowledge, part two entitled ‘Heresies in Epitome: How They Began and Whence They Drew Their Origin’. It is usually just cited as Heresies. His work, the ‘Fount of Knowledge’ is one of the most important single works produced in the Greek patristic period. It is the first great Summa of theology to appear in either the East or the West. Saint John (+ 749 AD) is considered one of the great Fathers of the Church, and his writings hold a place of high honor in the Church. His critique of Islam, or “the heresy of the Ishmaelites,” is especially relevant for our times.