This chapter analyzes the doctrine of ḥākimiyya in the writings of two twentieth-century thinkers, the Indo-Pakistani Abū al-Aʿlā Mawdūdī and the Egyptian Sayyid Quṭb. These authors were the first to articulate a consistent system in which the conflict between divine law and man-made law was considered the primary differentiator between faith and unbelief. Like the premodern monolatry tradition, Mawdūdī and Quṭb view monolatry (exclusivity of worship) as the essence of Islam; but they characterize exclusivity of obedience to Allāh’s legal sovereignty as the most important form of worship, thus converting the basic monolatry framework into a polemic against secularization. This theonomy doctrine was already fully elaborated in Mawdūdī’s writings in the 1930s and 1940s, which exhibit some familiarity with the premodern anti-taqlīd polemic and may have been influenced by it. Quṭb’s embrace of the doctrine in his final writings had a major impact on the emergent radical salafī tendency in the 1970s and 1980s and presaged the decisive split between these groups and the mainstream Muslim Brotherhood.