Furthermore, those who, having forsaken Scripture, imagine some way or other of reaching God, ought to be thought of as not so much gripped by error as carried away with frenzy. For of late, certain giddy men have arisen who, with great haughtiness exalting the teaching office of the Spirit, despise all reading and laugh at the simplicity of those who, as they express it, still follow the dead and killing letter.1 But I should like to know from them what this spirit is by whose inspiration they are borne up so high that they dare despise the Scriptural doctrine as childish and mean. For if they answer that it is the Spirit of Christ, such assurance is utterly ridiculous. Indeed, they will, I think, agree that the apostles of Christ and other believers of the primitive church were illumined by no other Spirit. Yet no one of them thence learned contempt for God’s Word; rather, each was imbued with greater reverence as their writings most splendidly attest. And indeed it had thus been foretold through the mouth of Isaiah. For where he says, “My Spirit which is in you, and the words that I have put in your mouth, will not depart from your mouth, nor from the mouth of your seed … forever” [Isa. 59:21 p., cf. Vg.], he does not bind the ancient folk to outward doctrine as if they were learning their ABC’s; rather, he teaches that under the reign of Christ the new church will have this true and complete happiness: to be ruled no less by the voice of God than by the Spirit. Hence we conclude that by a heinous sacrilege these rascals tear apart those things which the prophet joined together with an inviolable bond. Besides this, Paul, “caught up even to the third heaven” [2 Cor. 12:2], yet did not fail to become proficient in the doctrine of the Law and the Prophets, just as also he urges Timothy, a teacher of singular excellence, to give heed to reading [1 Tim. 4:13]. And worth remembering is that praise with which he adorns Scripture, that it “is useful for teaching, admonishing, and reproving in order that the servants of God may be made perfect” [2 Tim. 3:16–17]. What devilish madness is it to pretend that the use of Scripture, which leads the children of God even to the final goal, is fleeting or temporal?
Then, too, I should like them to answer me whether they have drunk of another spirit than that which the Lord promised his disciples. Even if they are completely demented, yet I do not think that they have been seized with such great dizziness as to make this boast. But in promising it, of what sort did he declare his Spirit would be? One that would speak not from himself but would suggest to and instill into their minds what he had handed on through the Word [John 16:13]. Therefore the Spirit, promised to us, has not the task of inventing new and unheard-of revelations, or of forging a new kind of doctrine, to lead us away from the received doctrine of the gospel, but of sealing our minds with that very doctrine which is commended by the gospel.
—John Calvin, Institutes of the Christian Religion, 1.9.1