This essay draws on an original study of the history, theories, and organizational life of Iran's most influential leftist organization in the 1970s, the People's Fedayee Guerrillas, to examine the symptomatic misconception of secularism as well as the secularization of everyday life and politics by a specific generation of Iran's Left. The essay argues that because of its ideological adherence to Marxism, the militant Left of this era simply assumed its role as a secular political force, while riveted by cultural elements that in fact undermined secularism. Moreover, it shows that a stark political dualism between the people and the shah's regime and its capitalist supporters caused the militant Left to advance a certain political binarism that later paved the way for the 1979 Islamic revolution, a phenomenon that indicates how the Left lost sight of the perils of political Islam or discounted its future impact on society. These arguments are complicated by the demographics and cultural inclinations of the members and supporters of the Fedayeen that indicate the extent of permeation of traditionalism and semireligious beliefs in the militant Left. These observations lead the author to inquire whether the Iranian Left has ever been consciously secular.