This pioneering study casts important new light on key issues in the development of dogmatic instruction in early Islam, as it examines the creed written by the Basran and Baghdadi Sunni preacher Ghulām Khalīl (d. 275/888). It includes a critical edition of the Arabic text and an English translation of what appears to be one of the earliest statements of religious beliefs in Islam. In particular, this book argues convincingly that this influential text was authored by the ninth century Ghulām Khalīl rather than the Hanbali preacher of Baghdad, al-Barbahārī - a claim repeatedly made by modern scholars, both Western and Eastern. The present publication broaches multi-layered themes with the aim of specifying the parameters of this “Muslim Creed” in terms of the composite relationship between its content and its origin. In addition, it tackles the important question of what may have led modern Salafis to embrace the doctrinal positions of this particular statement of belief and practice and, perhaps more importantly, to pursue its “institutionalization” as a religious orthodoxy.