In 781 A.D., a debate on the Christian and Muslim faiths took place over a period of two days between Mar Timothy I (780-823), Patriarch of the Assyrian Church of the East and the Abbasid Caliph Mahdi (775-785) in Baghdad. The record of this debate survives in an original Syriac version and later Arabic versions. This book contains the text of the Syriac version and an English translation by Alphonse Mingana. This debate is significant for a number of reasons. It provides a very early witness to the relations between Islam and Christianity. It is characterized by an open and honest sharing of ideas and beliefs that is often sadly lacking in later similar encounters, even in the present day. The participants demonstrate a high degree of respect for each other that extends to their often opposing beliefs. They tend to look for common ground but never ignore or trivialize their differences.