Is making an explicit distinction between politically moderate devout Muslims and political radicals empirically valid? If yes, in what ways do political moderates differ from political radicals? By systematically examining cross-national Muslim attitudes, this article scrutinizes the distinctiveness of politically moderate and politically radical Islam against the weight of empirical evidence. By drawing from extant theoretical linkages, we conduct a confirmatory factor analysis of cross-national survey data from 13 Muslim-majority states to test the fit of two widely theorized factors—moderate and radical Islamism. The findings suggest that support for politically moderate Islam is distinctively different from support for politically radical Islam. This article makes two key contributions. First, this study introduces a systematic empirical operationalization of Political Islam, and a more nuanced measurement thereof for empirical research. Second, the findings help advance our understanding of the variation in politically divergent religious attitudes in the Islamic world.