Categorization is an innate human ability that helps us understand and perceive the world around us. In this article, we explore how this ability affects how and why people, groups, and states around the world categorize Muslims. Our focus is primarily on the categories of moderate and radical, and the problems associated with these two distinctions. We argue that what counts as radical as opposed to moderate is always changing, because it depends on what is considered moderate at a particular time and place and is therefore also dependent on existing power arrangements. We also argue that the categorization of radical and moderate is linked to liberal values and liberal politics, rather than to theological beliefs.