The key intellectual fault line driving constitutional theory today is the tension between the limits of constitutionalism and the illimitability of constituent power. My paper situates this debate within Hindu and Muslim political thought in South Asia, recasting it as a clash between the prohibitive authority of law and the acquisitive force of sovereignty. I argue that the ethno-nationalist and socio-religious movements of Hindutva and Islamism have shaped the state in postcolonial India and Pakistan through two radically divergent trajectories: Hindutva reconfigures Hinduism substantially as a religion of sovereignty, while Islamism reinterprets Islam essentially as a religion of law. This marks a striking yet regrettable departure from the anticolonial moment, when modernist renditions of Hinduism and Islam treated the two concepts as inextricably entwined. Drawing upon the political thought of Savarkar, Maududi, Gandhi and Iqbal, and putting them in conversation with Kelsen and Schmitt, I establish that only by reckoning with law and sovereignty together can we sustain the political world as a collective space for a life in common.