They who strive to build up firm faith in Scripture through disputation are doing things backwards . . . Since for unbelieving men religion seems to stand by opinion alone, they, in order not to believe anything foolishly or lightly, both wish and demand rational proof that Moses and the prophets spoke divinely. But I reply: the testimony of the Spirit is more excellent than all reason. Some good folk are annoyed that a clear proof is not ready at hand when the impious, unpunished, murmur against God’s Word. As if the Spirit were not called both “seal” and “guarantee” for confirming the faith of the godly; because until he illumines their minds, they ever waver among many doubts!
Therefore, Scripture bears its own authentication. Let this point therefore stand: that those whom the Holy Spirit has inwardly taught truly rest upon Scripture, and that Scripture indeed is self-authenticated [by the Spirit]. Therefore, illumined by his power, we believe neither by our own nor by anyone else’s judgment that Scripture is from God; but above human judgment we affirm with utter certainty that it has flowed to us from the very mouth of God by the ministry of men.
Therefore we seek no proofs, no marks of genuineness upon which our judgment may lean; but we subject our judgment and wit to it as a thing far beyond any guesswork! If God has willed this treasure of understanding to be hidden from his children [to necessitate revelation for us to know Him], it is no wonder or absurdity that the multitude of men are so ignorant and stupid! Whenever, then, the fewness of believers disturbs us, let the converse come to mind, that only those whom it is given can comprehend the mysteries of God.
— selections from John Calvin’s Institutes of the Christian Religion, Ch. 7