As heirs of the Reformation, and in distinction from Roman Catholicism, we hold to the perspicuity of Scripture. This is the doctrine that any believer can, by the illumination from the Holy spirit, understand the Scriptures adequately to know what God would have him believe and do. In saying this, we do not mean that all Scripture is equally easy to understand. Some passages are, as Peter confessed, “hard to understand” (2 Peter 3:15–16). On this subject, in his Disputation . . . against the Papists, William Whitaker quotes none other than a pope, Gregory the Great (540–604), whom Calvin is said to have called “the last good pope.”

The very obscurity of the words of God is of great use, because it exercises the perception so as to be enlarged by labour, and, through exercise, be enabled to catch that which a lazy reader cannot. It hath besides this still greater advantage, that the meaning of sacred scripture would be lightly esteemed, if it were plain in all places. In some obscure places the sweetness with which it refresheth the mind, when found, is proportionate to the toil and labour which were expended upon the search.

—Gregory the Great, quoted in William Whitaker, Disputations on the Holy Scriptures (Soli Deo Gloria, 2005), 375.