"The very idea of Christianity in its profession and history, is something more than this; it is a 'Revelatio revelata' [revealed revelation]; it is a definite message from God to man distinctly conveyed by His chosen instruments, and to be received as such a message; and therefore to be positively acknowledged, embraced, and maintained as true, on the ground of its being divine, not as true on intrinsic grounds, not as probably true, or partially true, but as absolutely certain knowledge, certain in a sense in which nothing else can be certain, because it comes from Him who neither can deceive nor be deceived.
"And the whole tenor of Scripture from beginning to end is to this effect: the matter of revelation is not a mere collection of truths, not a philosophical view, not a religious sentiment or spirit, not a special morality,––poured out upon mankind as a stream might pour itself into the sea, miing with the world's thought, modifying, purifying, invigorating it;––but an authoritative teaching, which bears witness to itself and keeps itself together as one, in contrast to the assemblage of opinions on all sides of it, and speaks to all men, as being ever and everywhere one and the same, and claiming to be received intelligently, by all whom it addresses, as one doctrine, discipline, and devotion directly given from above. In consequence, the exhibition of credentials, that is, of evidence, that is what it professes to be, is essential to Christianity, as it comes to us; for we are not left at liberty to pick and choose out of its contents according to our judgment, but must receive it all, as we find it, if we accept it at all. It is a religion in addition to the religion of nature; and as nature has an intrinsic claim upon us to be obeyed and used, so what is over and above nature, or supernatural, must also bring with it valid testimonials of its right to demand our homage.
John Henry Cardinal Newman, in his Essay in Aid of a Grammar of Assent