What reason is there for belonging to the Catholic Church, or to any other church, for that matter? An answer that some people would give is: there may be plenty of good reasons, but there is no rationale. A good reason for belonging to the Catholic Church would be that you had always been a Catholic and that you felt at home in it; another would be that you were living in a Catholic country, and no other Christian church amounted to more than a sect there. These, of course, are personal reasons, applying to some people and not to others; as such, they contrast with any purported rationale. A rationale, if there was one, for belonging to a particular church would be a proposition holding good generally and not relating to certain individuals more than to others, that, in virtue of its truth, constituted a reason, perhaps a compelling reason, for belonging to that church rather than any other. Is it plausible to hold that there is no rationale, in this sense, for belonging to the Catholic Church, or, conversely, for not belonging to it?

We know that men and women have died rather than renounce, or rather than adhere to, the Catholic Church: if there is no rationale in the matter, they were pitiably deluded. There is no sense to be made of the history of Christianity unless we regard one proposition as held in common by Catholics and Orthodox, and rejected by Protestants.