Although fundamentalism is neither new nor limited to one culture, globalized communications and recent political events have highlighted Christian and Muslim forms. Since links are often perceived between fundamentalism, extremism and terrorism, most commonly with respect to Islamic fundamentalism, it is desirable to delineate a model of fundamentalism which permits some degree of prediction as to its possible extension into political action. The term ‘religious fundamentalism’, it is argued here, can denote a type of worldview that can in fact be found in various religions of the world of today. Specifically, it may denote a shift in mentality from the relative harmlessness of an otherwise quaint, ultra-religious belief system to the readiness to pursue aggressively impositional, and in some cases terrorist activity. The article seeks to work out the details of these potential connections paradigmatically.