So, I said a while back that I wanted to see what the various historical confessions had to say about biblical authority. Here's Westminster:
...Although the light of nature, and the works of creation and providence do so far manifest the goodness, wisdom, and power of God, as to leave men unexcusable; yet are they not sufficient to give that knowledge of God, and of His will, which is necessary unto salvation. Therefore it pleased the Lord, at sundry times, and in divers manners, to reveal Himself, and to declare that His will unto His Church; and afterwards for the better preserving and propagating of the truth, and for the more sure establishment and comfort of the Church against the corruption of the flesh, and the malice of Satan and of the world, to commit the same wholly unto writing; which makes the Holy Scripture to be most necessary; those former ways of God's revealing His will unto His people being now ceased...
.
The authority of the Holy Scripture, for which it ought to be believed, and obeyed, depends not upon the testimony of any man, or Church; but wholly upon God (who is truth itself) the author thereof: and therefore it is to be received, because it is the Word of God. We may be moved and induced by the testimony of the Church to an high and reverent esteem of the Holy Scripture. And the heavenliness of the matter, the efficacy of the doctrine, the majesty of the style, the consent of all the
parts, the scope of the whole (which is, to give all glory to God), the full discovery it makes of the only way of man's salvation, the many other incomparable excellencies, and the entire perfection thereof, are arguments whereby it does abundantly evidence itself to be the Word of God: yet notwithstanding, our full persuasion and assurance of the infallible truth and divine authority thereof, is from the inward work of the Holy Spirit bearing witness by and with the Word in our hearts.
The whole counsel of God concerning all things necessary for His own glory, man's salvation, faith and life, is either expressly set down in Scripture, or by good and necessary consequence may be deduced from Scripture: unto which nothing at any time is to be added, whether by new revelations of the Spirit, or traditions of men. Nevertheless, we acknowledge the inward illumination of the Spirit of God to be necessary for the saving understanding of such things as are revealed in the Word: and that there are some circumstances concerning the worship of God, and government of the Church, common to human actions and societies, which are to be ordered by the light of nature, and Christian prudence, according to the general
rules of the Word, which are always to be observed.
Now Westminster is not gospel, but it is, so far as I can tell, a faithful summary of the Gospel, and here it is basically saying that you cannot prove the infallability of the Bible. Of course, we believe that the bible is authoritative, inspired, inerrant, and infallable, but convincing someone of that is purely an act of the Holy Spirit. That is, an act of God himself. Some folks will believe these things about the Bible and some folks won't and the difference is wholly in who the Holy Spirit induces this belief. Where did the authors of Westminster come up with this understanding of the authority of scripture?
However, as it is written: "No eye has seen, no ear has heard, no mind has conceived what God has prepared for those who love him" but God has revealed it to us by his Spirit. The Spirit searches all things, even the deep things of God. For who among men knows the thoughts of a man except the man's spirit within him? In the same way no one knows the thoughts of God except the Spirit of God. We have not received the spirit of the world but the Spirit who is from God, that we may understand what God has freely given us. This is what we speak, not in words taught us by human wisdom but in words taught by the Spirit, expressing spiritual truths in spiritual words. The man without the Spirit does not accept the things that come from the Spirit of God, for they are foolishness to him, and he cannot understand them, because they are spiritually discerned. (1st Corinthians 2:9-16; NIV)
Of course, this is not the only passage that leads us to believe that the Bible is authoritative, inspired, inerrant, and infallable. Such passages are scattered throughout the whole, and it is not always the denotated meaning of the passages, but the tone, or connotation of the Bible. The Holy (meaning 'uniquely') Spirit of the thing. (as in the saying 'Spirit of the Law').