The interpretation of a text is aided by a proper understanding of a set of principles, among them the scope of the passage. Unless proper weight is given to its scope—interpretation cannot produce an accurate result…Biblical texts ripped out of their context can be made to say and teach anything; the same texts understood in light of the design of the author engender orthodoxy.
The Scope of the Whole
We have already cited the common language of the great English Protestant Confessions, Presbyterian, Independent and Baptist; we are now prepared to consider their relevant words. Among the attributes of Scripture is the fact of its scope:It gives all glory to God. This brief statement allows us to conceptualize the Puritan notion of scope–all of Scripture points to the glory of God. Its purpose is, at all places, a demonstration of God’s glory. While this may be hidden to blind eyes, and only received by a work of the Spirit, it is nevertheless certain. Divine origination and thus divine authority provides Scripture with a reflexive quality. In all of its parts its purpose is to glorify God. The divine author has ensured that it always aims at this target; that it always points to this compass position.
This is not to say that the only way to view the scope of the whole is in light of the glory of God narrowly defined, for that does not reflect the totality of the Puritan vision. In a fascinating paragraph that largely parallels the statement of the three Confessions cited above, John Owen (who played a principal role in the editing and publication of the Savoy Declaration) speaks to the subject. He says:
“I deny thee not the testimony of the universal church of Christ in all ages, so far as thou art capable of knowing it, as well as of the present church, or any particular one to which thou art any way related, as a help to thee: make the best thou canst of it, only rest not on it. But especially take notice, if thou see not the stamp of God upon the word, characters of divinity imprinted on it, as well as external notes accompanying it, consider the antiquity of it, the continuance of it, the miracles that confirmed it, the condition of the men that penned it—their aims, their carriage and conversation—God’s providence in keeping it and handing it down to thee through so many successive generations, when so many in all ages would have bereaved the world of it. And, farther, consider the majesty and gravity, and yet plainness and simplicity, of its style; the depth of the mysteries it discovers, the truth and divineness of the doctrine it teacheth, the spirituality of the duties its enjoins, the power and force of the arguments with which it persuades, the eternity of the rewards it promises and the punishments it threatens; the end and scope of the whole,–to reform the world, to discountenance and extirpate wickedness, and promote holiness and righteousness, and thereby advance God’s glory, and lead man on to everlasting blessedness, etc.” 
This is, too a large degree, a comment on the Confessional paragraph. As such, it expands the sense given to the succinct statement in the theological symbol. Owen defines the nature of the “scope of the whole” in three terms, all related to God’s glory and the reception of eternal blessedness for humanity. The terms are simply “to reform the world, discountenance and extirpate wickedness, and promote holiness and righteousness.” By themselves, one might think that Owen has slipped into moralism–teaching that the purpose of Scripture may be reduced to moral reform, the conquest of evil, and the promotion of righteousness. But to do this divorces his words from his thought at large, and from this sermon in particular. The excerpt we have cited comes almost at the end of a lengthy discourse titled “The Testimony of the Church is not the only nor the Chief reason of our Believing the Scripture to be the Word of God.” It is a defense primarily against Romanist assertions that the testimony of the teaching magisterium is the sole basis upon which to receive the Scripture as the Word of God. The very first sentence of the sermon is this: “An everlasting blessedness—men’s greatest and most desirable good—is that which God only can bestow, and the way to it, that which he only can discover.” The vindication of the Protestant doctrine of Scripture is couched in this context–a divine act is the great necessity for man’s salvation. Owen does not descend into moralism, rather he summarily points to the work of God in granting redemption to humanity. This is the context of his remarks.
It is necessary to insist that there is a further step to identify in this process, which is to say that in agreement with Athanasius, the English Reformed confessors understood their statement to imply that Christ is the scope of all Scripture. This is evident in at least two ways. First, the Reformed authors, following the text of Holy Writ, argue that Christ is the incarnation of the glory of God. If the scope of Scripture is to give all glory to God, and all glory comes to God through Him, then by definition this statement must have reference to the person of Jesus Christ. Secondly, they recognized the intimate relationship present between the two testaments and their constituent books. The Old, whether considered as a whole or in its parts, is an anticipation of the work of God in Christ. From the protevangelium through the historical revelation of the Covenant of Grace in the history of Israel, everything looked forward to his coming. Likewise, the New is the full revelation of the promises progressively revealed in the Old. This unity finds it fullness in Jesus Christ and his work. In every place, the Bible points to Christ—he is the target—the scope of Scripture. Perhaps Benjamin Keach best articulates this point:
“Now the mystery of Godliness principally consists in the person of Christ, God manifest in the flesh…When we know Christ better, we shall understand the mystery better: Christ is the mystery wrapt up in the Gospel, he is the scope of all the Scripture, the pearl hid in the field; every line is drawn to him, as the proper center; all the types and shadows pointed to him, and all the promises run in him. Jesus Christ is really and truly God, and yet very Man, God and man in one person, and is this not a mystery?”
This is the language of Athanasius and the great Confessions, expressed in popular terms by a leading Particular Baptist. Where does Scripture always point? To Christ.
The Scope of the Parts
While these expositors understood that the parts have reference to the whole, they did not restrict their understanding and use of the notion of scope simply to the whole. We may also speak of the scope of the parts: testament, book, chapter, pericope, verse and even phrase. In every case, the basic idea is the same. We have suggested the scope of each testament: the Old anticipates the coming of Christ; the New fulfills the promise. Within each Testament, the canonical books serve that purpose. While the scope of the whole is to bring all glory to God, the scope of the particular book within its Testament points to the fulfillment of God’s purposes in Christ, whether through anticipation and preparation or accomplishment and consummation.
This method is carried on through each of the constituent parts of the text. When one studies an individual book, one must first identify the scope of the book—generally the purpose at hand as expressed by the author. If a smaller section is under observation, the expositor still must seek to determine the target to which that section points—what is the purpose of the writer in putting this (pericope, phrase, word etc.) in this place? When the student determines that fact, his exposition will be governed by this principle. Whether this is evident in a positive exposition of a book of Scripture, or in an exegetical discussion within a theological treatise, frequent reference is made to the idea of scope. One does not have to look long to find instances.
In William Perkins’ Exposition of Jude, the very first item addressed is the scope of the book: “the generall ayme and scope of this epistle, is partly to declare the duty of all Christians, and partly to set out the corruptions of those, and these dayes and times; in both which every one may receive edification, who are desirous either to follow the former, or avoid the latter.”
Similarly, William Bradshaw’s Exposition of 2 Thessalonians begins with these words: “The principall scope of this Epistle is, to confirme and strengthen this Church in the sincerite of that Faith and Religion wherein it was first planted, and therein to arme it against all trials and temptations arising either from wicked Persecutors, or corrupt and antichristian Seducers.”
These are simply examples, which could be easily multiplied. Commenting on Perkins’ use of scope in his Galatians exposition, Sheppard says that it is “an indicator of how the content can be read in support of an authoritative argument.” For expositors such as these, the identification of this target served an important role in their own understanding and communication of the meaning of the text. Interpretation was to be governed by rules, and in this case, by a constant awareness of the design, or goal, or purpose of the text. In this way, they could ensure that the parts always supported the argument of the whole, could not be misused, and produced a consonant theological result. Perhaps one might think of a symphony. A wide variety of instruments, each given specific parts, together present a harmonious blend of music. The conductor’s goal is to ensure that each one fulfills its task properly with reference to the composer’s purpose in the musical score. For solo instruments the circumstances might be different, but as parts of an orchestra, their function is to contribute to the overall composition. The expositor is, in a sense, a conductor. His task is to understand the contribution made by the part with reference to the whole, ensuring that this is the role it fulfills, and no other. He must always be subject to the will of the divine composer. Musical misdirection produces cacophony, not harmony. Theological misinterpretation produces heterodoxy, not orthodoxy.
Of course, when Perkins or Bradshaw or any other commentator identified the scope of a particular book, they were not denying that the book itself always served as a compass needle pointing to the larger scope of the canon—the glory of God in Jesus Christ. This was always first and foremost—the book served the divine purpose of the corpus of Scripture. They were simply recognizing the occasional nature of each book within that larger sphere.