The phenomenon of religious exclusivism increasingly confronts peoples of faith and goodwill who wish only for peaceful co-existence in equality and freedom with their religious neighbour. But there is more than one variety of religious exclusivism. This study will show that there are at least three variants of religious exclusivism, namely open, closed and extreme. Further, inasmuch as exclusivism indicates a positing of religious identity over against any “other”, then it will be argued that the variant exclusivisms themselves reflect a continuum of ideological and theological stance that is taken toward the concept of variety as represented by the religious “other” per se. This ranges through antithetical acknowledge-ment, enactive ignorance, and the intentional invalidation of variety. It is the issue of the invalidation of otherness which, I contend, constitutes the severe theological problem of religious exclusivism in extremis. It is here, in the modality of religious fundamentalism and extremism that theological ideology impinges most dramatically upon the public domain. Might it be possible to speak of a proper religious exclusivity without falling necessarily into the pit of exclusivist extremism? In addressing this question I shall briefly examine the views of Alvin Plantinga, Gavin D’Costa, and the declaration Nostra Aetate of Vatican II.