Commenting on the Protestant doctrine of the “internal testimony of the Holy Spirit” to authenticate the Bible, Bernard Ramm wrote:
We believe that God persuades of divine truth, and that therefore on both the outside and the inside, objectively and subjectively, we are dealing with divinity. This does not mean that God avoids earthly instruments, but rather that he enters them from the inside (mysteriously) and by them persuades us. This persuasion is not mystical nor magical nor theological legerdemain; but in our hearts the earthly medium receives such a divine reinforcement that the faith which is engendered is faith upon divine authority.
Concretely, what we have here is the testimonium. We have been efficaciously persuaded by the divine Spirit about the divine truth in a divinely inspired book. On the objective side, the subjective side, on the part the book, we are confronted with the divine. Therefore we may say that faith is prompted by a divine Spirit and is directed toward a divine truth. It is faith in the authority of God, and on the authority of God.
Nor must we fail to note that faith is made for Scripture and Scripture for faith. When God gave Scripture, he gave it so that it would be a fit object for faith (i.e., autopistic). And when he prompts faith, he prompts it in such a way that the believer becomes hungry for Scripture. He wants to live by every word which proceeds from the mouth of God (Matt. 4:4). He desires the “pure spiritual milk” (to logikon adolon gala, 1 Peter 2:2) of Sacred Scripture and as he matures he is ready for “solid food” (stereas trophē, Heb. 5:12). For with David “his delight is in the law of the Lord, and on his law he meditates day and night” (Ps. 1:2). (Bernard Ramm, The Witness of the Spirit: An Essay on the Contemporary Relevance of the Internal Witness of the Holy Spirit [Grand Rapids, Mich.: Eerdmans, 1959], 71-72, italics in original)