One of the most common misunderstandings about Islam is that it contains some kind of essential ‘core’ which dictates the fundamental nature of political movements adopting its banner. Islam is one of the three ‘Abrahamic’ religions, along with Judaism and Christianity. While Christianity sees itself as a ‘refinement’ of Judaism, Islam sees itself as the final revelation in that line. This chapter looks at key theological and legal aspects of Islam, and to its practical historical manifestations, with a particular focus on Sunni Islam, a similar analysis can be carried out in relation to the Shi’a world. It suggests two key conclusions: first, that Islam has often been moulded for political goals by both rulers and their opposition; and second, that such manifestations, in all their ‘extremist’, ‘conservative’, or ‘progressive’ diversity, must be understood as a product of their political contexts. The chapter covers considerable territory, ignoring much that falls under the rubric of ‘Islam and Politics’.