At the time of Shahab Ahmed's untimely death on 17 September 2015, he left behind many admiring colleagues, students, friends, and family, as well as a weighty tome of monumental significance—What Is Islam? The Importance of Being Islamic. It is tragic when an author's first book is published posthumously, perhaps even more so in this case given that Ahmed's work is poised to have a pervasive influence on the field of Islamic Studies and has already garnered numerous accolades. Like a supermassive celestial body, this dense book exerts an irresistible attraction and alters the intellectual trajectory of those drawn into its orbit. What Is Islam? poses difficult questions no one in the field can ignore, even if one disagrees with its premises, methods, or conclusions. We are collectively the poorer for being unable to engage directly with the author in the many discussions that are sure to be provoked by the book's meteoric impact.