For nearly a century the term ‘fundamentalism’ has referred primarily to a set of specific Christian beliefs and an allied ultra-conservative attitude. However, usage of the term has broadened: ‘fundamentalism’, as a term indicating the position of a ‘closed mind’ coupled with a negative – even hostile – stance toward the status quo, has migrated into political discourse and the wider religious realm. Fundamentalism broadly names a religio-political perspective found in most, if not all, major religions. Most disturbingly, it is now associated with variant forms of religious extremism and thus religiously-oriented terrorism. And it is Islamic modalities of terrorism that, rightly or wrongly, have come to take centre-stage in current world affairs. This lecture will argue that the religious fundamentalism with which Islamist extremism is associated follows an identifiable paradigm that has wider applicability. Religious ‘fundamentalism’ denotes, among other things, a paradigm that paves the way from the relative harmlessness of an idiosyncratic and dogmatic belief system, to the harmful reality of religiously driven and fanatically followed pathways to terrorist activity. The lecture will attempt to describe and analyse this paradigm with reference to contemporary concerns.