Militant Islamist Sayyid Imam's legal critique of Al Qaeda's anti-U.S. mass casualty terrorism holds great potential utility for counterterrorist messaging strategy. In this article, a jihad–realist Islamist theological–jurisprudential methodology is first defended as the means most productive for delegitimizing Al Qaeda among high value, religiously motivated recruits. Second, Sayyid Imam's specific allegations and detailed Sharia proofs against Al Qaeda are presented. Finally, implications are drawn for U.S. counterterrorist messaging focusing especially on the utility of wielding this theological–juridical approach as compared to other “counternarrative” approaches, and the vital need to accurately characterize Islamism and its relation to terrorism.