Abstract: This paper rebuts the thesis that political Islam conflicts with secular democracy. More precisely, it examines three sorts of claims that ostensibly support this thesis: (a) The Muslim religion is incompatible with secular democracy; (b) No Muslim country has instituted secular democracy; and (c) No movement seeking to advance its agenda as aggressively as political Islam does can do so with the degree of moderation required of a political party that is committed to secular democracy. Theologians, philosophers, and political scientists have debated (a) through (c) within the jurisdiction of their respective fields. I propose to combine these debates in developing what I hope will be a novel interdisciplinary examination of the relevant issues. The paper compares different types of Muslim regimes, different models of secular democracy, and different conceptions of public reason, and concludes with a comparison between Catholicism and Islam regarding the relevant question.