Mīrzā Fatḥ ‘Alī Ākhūndzāda’s Letters from Prince Kamāl al-Dawla to the Prince Jalāl al-Dawla (1865) is often read as a Persian attempt to introduce European Enlightenment political thought to modern Iranian society. This essay frames Ākhūndzāda’s text within a broader intellectual tradition. I read Ākhūndzāda as a radical reformer whose intellectual ambition were shaped by prior Persian and Arabic endeavors to map the diversity of religious belief and to critically assess the limits of religion. That Ākhūndzāda’s critique of religion reached further than that of his predecessors is due in part to the influence of the European Enlightenment, but Ākhūndzāda’s form of critical reasoning was also substantially shaped by prior early modern intellectual genealogies.