Following the September 11, 2001 suicide attacks, numerous Western policymakers and scholars have socially and ideologically constructed and homogenized Islam with violent practices of suicide-terrorism. They covertly propagate Islam as a violent religion despite its deep moral denouncement against the criminality of such practices. This paper investigates how and when religious diplomacy influences modern-day khawarej within the Islamic world. Drawing from two case studies — Taliban and Al Qaeda – I argue that religious diplomacy is an essential diplomatic instrument to effectively undermine the khawarej by significantly improving coercive tactics if constructive diplomacy fails. By employing a hermeneutical approach, I examine the conditions under which jihad (jus ad bellum/jus in bello) become reasonably permissible, while analysing Islamic fatawa on suicide-terrorism and the limitation of these religious verdicts. These critical assessments are significantly relevant, as religious ignorance, wrongful possession of modern technology, and hidden geopolitical interests erroneously promote anti-Islamic ideologies globally.