Introduction: The Uncomfortable Correlation The claim is blunt, intentionally provocative, and for many, deeply offensive. Yet, the idea that religious belief is linked to lower intelligence is not merely an insult hurled in the heat of debate; it is a question that has been the subject of scientific inquiry for nearly a century. Research into the relationship between cognitive ability and faith began as early as the 1920s, and since then, a substantial body of evidence has accumulated, point...