This study explores the ways in which theological ideas regarding the nature of God shaped the jurisprudential and legal landscape of Islam. Focusing on the traditionalist theological and jurisprudential thought of Ibn Taymiyyah (d. 728/1328) and Ibn al-Qayyim (d. 751/1350), this study traces the way in which these towering scholars critiqued the dominant theological-jurisprudential tradition of their day, which was influenced by dialectical theology. Against the dialectical theologians, Ibn Taymiyyah and Ibn al-Qayyim argued that an authentically fideist, consistent and rational theory of Islamic law could only emerge from an acceptance of the reality of God’s voluntary attributes.