This article is a study and analysis of Dirar b. 'Amr's Kitab at,Tahrish demonstrating the religious and sectarian diversity of, as well as differences among, the Muslims of the second century AH. The article examines the author's method in presenting the disagreements of his age and analyzes his position on these disagreements. It also sheds light on the topics covered by this book – which was lost – covering various issues in various fields of the Islamic sciences. It also presents an analysis of how the author evaluated the disagreements of his age and his attempt to establish a yardstick by which to evaluate differences between sects. The article concludes that Kitab at,Tahrish narrates historical truths most of today's Muslims are oblivious to, awareness and revitalization of which is urgently necessary in their present,day lives. The most important of these truths are that the perception of a harmonized unified Muslim vision in the early centuries has no foundation in fact, and that differences have existed and will always exist for both intellectual reasons and external reasons attributable to the exploitation of religion by some religious scholars for their own personal gain, for the acquisition of wealth, authority and prestige.