Many Christians are exclusivists by which I don’t mean that they are social snobs or against racial integration. Rather, an “exclusivist” is one who believes that certain things are essential to being saved by Jesus.
Catholic Community Exclusivism
Historic Catholicism (i.e. prior to Vatican II) tended to be exclusivist about membership in its own institution. That is, only people who were members of the Catholic Church could be saved. Thus the very influential medieval Pope Innocent III declared: “There is but one universal Church of the faithful, outside which no one at all is saved.” And by universal church he was referring to a visible institution headquartered in Rome. Similarly Thomas Aquinas wrote “There is no entering into salvation outside the Church, just as in the time of the deluge there was none outside the ark, which denotes the Church.” So the extent to which one believed the Church was identical with the Roman Catholic Church one would have been an exclusivist: membership in that church is essential to salvation. The Catholic Church no longer takes such a view (though some within it no doubt do).