The two sides in the present controversy concerning scriptural authority  are becoming increasingly polarized. On the one hand, there are those  who view the Bible as only edifying religious literature and Jesus  Christ as the most profound of all human prophets. Inspiration in these  circles connotes nothing more than a general illumination that all  spiritually sensitive people share to some degree. It is therefore not  uncommon to hear it alleged that some Christian classics or even  devotional masterpieces in other religions are inspired by the Spirit of  God in the same sense as Scripture.
On the other hand, there are those who in their zeal to safeguard the  divine authority of Scripture define inspiration in terms that approach  mechanical dictation. In this view the Bible becomes a celestial tape  recorder, and its true humanity is thereby denied. The inerrancy of  Scripture is affirmed in the sense of mathematical or scientific  precision which allows for no inconsistencies in the details of what is  reported. The focus is no longer on the divine content but on the mode  of expression by which Scripture comes to us. The language of the text  is regarded as flawless as historical science understands this term.
There is an important sense in which the Scripture does not err: it does  not err in what it affirms concerning the law and gospel, the two sides  of the revelation of God. It does not err in what the Holy Spirit  intends to teach us in and through the biblical text, and this teaching  extends to the truth about man and the world as well as the truth about  salvation. The Psalmist declares: ‘The sum of thy word is truth’  (119:160; cf. Is. 45:19; Jn. 17:17). Paul insists that he is ‘speaking  the truth in Christ, I am not lying’ (Rom. 9:1). In the pastoral  epistles the truth handed down by the apostle is described as  trustworthy (pistos) and deserving of full acceptance (1 Tim. 1:15; 3:1;  4:9; 2 Tim. 2:11; Tit. 3:8). Similarly in the fourth gospel we read:  ‘This is the disciple who is bearing witness to these things … and we  know that his testimony is true’ (Jn. 21:24; cf. 19:35).
Scripture does give a wholly reliable and trustworthy account of God’s  dealings with man in biblical history. Yet this does not mean that  everything in Scripture must be taken at face value. Nor does it mean  that the human authors of Scripture were taken out of their cultural and  historical milieu and thereby rendered free from human limitations.  They were both children of their times and prophets to their times.
Inspiration should be understood as the divine selection of the writers  and their writings for the purpose of intruction in salvation and  training in righteousness. It does not mean that the Holy Spirit  overruled the personalities of the human authors; instead he worked in  and through them. Our Reformed fathers referred to the accommodation of  the Spirit to the language and concepts of that time. This means that  there is something of the provisional and relative in the Bible, even  though its message and teaching derive from God himself.
In this light we should understand that the Bible in and of itself is  not revelation, but revelation is given in the Bible. It is not the  letter that is the truth but the Spirit acting upon the letter (1 Cor.  2:4; 2 Cor. 3:6). The criterion for faith is the Spirit speaking in and  through the text of Scripture. As Zwingli retorted when John Faber  declared that there must be a judge, ‘The Spirit of God out of Holy  Scripture itself is the judge’ (The New Cambridge Modern History: The  Reformation 1520–59, II, p. 101).
In order to hear and know the veritable Word of God, in order to  perceive the Spirit-intended meaning of the words, we must search the  Scriptures. We must ‘dig out’ the truth that is contained in the  Scriptures (Dwight L. Moody). We must seek the spiritual discernment  necessary to apprehend spiritual truths (1 Cor. 2:9–16). As the Psalmist  declares: ‘Open my eyes, so that I may see the wonderful truths in your  law’ (Ps. 119:18 GNB; cf. Lk. 24:45). The Word of God is likened to a  ‘rich treasure’ that one must ‘find’ or uncover in the Scriptures (Ps.  119:162 GNB).
The Bible is not a systematic set of rules that can be immediately  perceived and then applied. It is more like a uranium mine that yields  its precious metal only after a careful and painstaking search. The  interpretation of Scripture is a work of faith; it is not intended for  those who refuse to exert themselves and submit themselves to the  guidance and direction of the Spirit. John Chrysostom observed that the  meaning of the scriptural text often ‘lies buried at a great depth’;  indeed, only special enlightenment from the Holy Spirit can enable one  to apprehend it.
The authority of the Bible is derivative: it is anchored not in itself  but in its divine Author and divine centre, Jesus Christ. It is a  signpost that points to Jesus Christ, and at the same time it is a  vessel that carries the truth of Jesus Christ. Luther described it as  the ‘carriage of the Spirit’. He also referred to Scripture as the  ‘swaddling clothes’ in which the Christ-child is laid.
The most potent symbol for the Word of God is not the book itself but  the cross of Christ shining through the pages of the open Bible. For it  is Jesus Christ whom the Bible attests; it is his salvation that the  Bible proclaims and conveys. According to Calvin the promises of God are  ‘sure and infallible’ only when we ‘resort always to Jesus Christ’  (Sermons on Ephesians, Banner of Truth, 1973, p. 176).
We need to recognize again that the Bible has two sides: a divine and a  human side. It is a human witness to divine revelation, for as 2 Peter  says, men spoke from God (1:21). But at the same time it is God’s  self-revelation through human authors; as the Epistle to the Hebrews  expresses it, God spoke to men (Heb. 1:2). The Bible is the Word of God  indirectly—in and through the words of men.
Calvin rightly described the Bible as the ‘unerring rule of faith and  practice’. The certainty of its truth, he said, is derived from the  interior witness of the Spirit. The majesty of its doctrine also argues  for its truth, though this can be perceived only by faith.
It is a mistake to appeal to external evidences to buttress or prove the  divine authority and inspiration of the Scriptures, for the Bible  authenticates itself. It carries its own credentials. This must not be  taken to mean, however, that the claims of the Bible are persuasive  because of their logical force or rational coherence. Instead they  persuade and convict because the Spirit of God inheres within the book  that he inspired. The text of Scripture is the property of its divine  author who alone can regenerate and renew sinful humanity.
I do not wish to imply that external evidences in support of Scripture  are of no value whatsoever. They may indeed cast new light upon the  Bible and confirm its claims concerning itself, but this confirmation is  given only to those who already believe. Archaeology has shown the  amazing accuracy of the Bible even in many of its historical details,  but this does not and cannot prove its perfect accuracy in this regard.  Neither can archaeology or historical science establish the divine  authority and inspiration of Scripture.
The authority of Scripture is rooted not in the manner of its writing  but in the way it is applied by the Spirit to direct us to Christ. Its  divine-human origin is subordinate to its salvific role or function. The  inspiration of the text of Scripture is in the service of the  communication of its message. Scripture is best seen as a human medium,  prepared by the Spirit, through which we come to know the benefits of  Christ. It is not just a human witness to Christ but a divinely  appointed means through which we receive saving knowledge of Christ.  These writings were designed to make us ‘wise unto salvation’ (2 Tim.  3:15 KJV).
The Bible might be likened to a drinking fountain whose water is drawn  from an underground spring. The water of life is hidden, and we  therefore have access to it only by means of this fountain. Unless we go  to the fountain and drink from it, our spiritual thirst will not be  satisfied. It may still be a beautiful structure, it may even have  historical or scientific value, but it will not be the fount of  salvation. It is not enough to appreciate the literary style of the  Bible or even its doctrinal profundity: we must experience its  life-giving power.
Donald Bloesch, “The Sword of the Spirit: The Meaning of Inspiration,” Themelios, No. 3, May 1980 5 (1980): 15–16.