"Defining Islam: A reader" aims to present original source material and scholarly reflections on how the word "Islam" is to be used and understood. Ever since a group of people came into existence who called themselves Muslims, questions of what it meant to be a member of that group, who was to be included and who excluded, and what the requirements for membership were, have proven to be both divisive and defining for the community itself. Likewise for scholars, the issue of what constitutes "Islam" when they talk about the emergence of the religion or when they compare local traditions or when the media debates whether the phrase "Muslim terrorist" is meaningful or appropriate, is always a central one for debate.