This article examines the Islamic concept of takfīr (the declaration that one is not a Muslim) as it is used in secular-pluralistic contexts, within a larger delegitimizing discourse against terrorism. I argue that this takfīr as deployed by “liberal” Muslims, functions to legitimate the state’s use of coercive force. Furthermore, the secular state may in turn draw upon these discourses to co-opt the right to determine authentic Muslim identity. However, in doing so the state is forced to enter into a religiously discursive space. Takfīr notably becomes the site of contention over secular state sovereignty for determining the value of life, where religious individuals both challenge and affirm this sovereignty. This reveals the dynamics in the relationship between secular conceptions of sovereignty and religion, as it pertains to the justification of violence.