The difficulty of explaining “why I am a Catholic” is that there are ten thousand reasons all amounting to one reason: that Catholicism is true. I could fill all my space with separate sentences each beginning with the words, “It is the only thing that…” As, for instance, (1) It is the only thing that really prevents a sin from being a secret. (2) It is the only thing in which the superior cannot be superior; in the sense of supercilious. (3) It is the only thing that frees a man from the degrading slavery of being a child of his age. (4) It is the only thing that talks as if it were the truth; as if it were a real messenger refusing to tamper with a real message. (5) It is the only type of Christianity that really contains every type of man; even the respectable man. (6) It is the only large attempt to change the world from the inside; working through wills and not laws; and so on.
Or I might treat the matter personally and describe my own conversion; but I happen to have a strong feeling that this method makes the business look much smaller than it really is. Numbers of much better men have been sincerely converted to much worse religions. I would much prefer to attempt to say here of the Catholic Church precisely the things that cannot be said even of its very respectable rivals. In short, I would say chiefly of the Catholic Church that it is catholic. I would rather try to suggest that it is not only larger than me, but larger than anything in the world; that it is indeed larger than the world. But since in this short space I can only take a section, I will consider it in its capacity of a guardian of the truth.
The other day a well-known writer, otherwise quite well-informed, said that the Catholic Church is always the enemy of new ideas. It probably did not occur to him that his own remark was not exactly in the nature of a new idea. It is one of the notions that Catholics have to be continually refuting, because it is such a very old idea. Indeed, those who complain that Catholicism cannot say anything new, seldom think it necessary to say anything new about Catholicism. As a matter of fact, a real study of history will show it to be curiously contrary to the fact. In so far as the ideas really are ideas, and in so far as any such ideas can be new, Catholics have continually suffered through supporting them when they were really new; when they were much too new to find any other support. The Catholic was not only first in the field but alone in the field; and there was as yet nobody to understand what he had found there.
—from Twelve Modern Apostles and Their Creeds (1926)