. . . the argument for Christianity must . . . be that of presupposition. With Augustine it must be maintained that God’s revelation is the sun from which all other light derives. The best, the only, the absolutely certain proof of the truth of Christianity is that unless its truth be presupposed there is no proof of anything. Christianity is proved as being the very foundation of the idea of proof itself.
—Cornelius Van Til, The Defense of the Faith, p. 396