The perspicuity of Holy Scripture is something quite central to the Protestant Reformation, in principle. In other words, for the
Protestant Reformers and reformed, the clarity of Scripture as to things having to do with who God is and what salvation entails is absolutely central to the capacity for all believers to fulfill the Reformed principle of the Priesthood of All Believers. Note what the Westminster Confession of Faith 1/VII & 1/IX communicates:
VII. All things in Scripture are not alike plain in themselves, nor alike clear unto all: yet those things which are necessary to be known, believed, and observed for salvation are so clearly propounded, and opened in some place of Scripture or other, that not only the learned, but the unlearned, in a due use of the ordinary means, may attain unto a sufficient understanding of them.
X. The infallible rule of interpretation of Scripture is the Scripture itself: and therefore, when there is a question about the true and full sense of any Scripture (which is not manifold, but one), it must be searched and known by other places that speak more clearly.
But as we look out on the horizon of present day Protestant exegesis of the Bible, it becomes quickly apparent that something has gone awry; that what sociologist Christian Smith calls Pervasive Interpretive Pluralism is surely pertinent to our current circumstances (i.e. the idea that there are as many interpretations of the text of Scripture as there are interpreters or communities of interpreters).
So is the WCF wrong in its view of the clarity of Scriputure? Were the Reformers wrong in pressing this idea of the perspicuity of Holy Writ? Not necessarily, but maybe we need to take some of those principles and hone them more sharply; maybe we need to identify a canon or standard by which we can identify what clarity actually looks like, and who controls that when we engage with Scripture. And maybe we need to consider the reality (as the WCF does) that sin still clouds things such that we must look even beyond Scripture, through Scripture, for the clarity that Scripture bears witness to. And maybe we should consider Scripture’s clarity as an eschatological and even apocalyptic reality that is not a static thing but a dynamic thing as we are all (as the church) growing more and more in the grace and knowledge of Jesus Christ. Todd Billings (with John Webster’s help) helps clarify my points further:
It is in this context that the notion of Scripture as “self-interpreting” is properly understood. Though this notion that Scripture is “self-interpreting” and “clear” is often criticized as naïve, it is better thought of as a way to understand the priority of God’s word by way of Scripture standing over the reader and all that the reader brings to the text. As John Webster says, “Scripture is self-interpreting and perspicuous by virtue of its relation to God; its clarity is inherent, not made, whether by magisterial authorities, the scholar-prince or the pious reader.” Webster, Holy Scripture, p. 93. This self-interpreting clarity is not a formal property of the biblical text; rather, “Scripture is clear because through the Spirit the text serves God’s self-presentation. Properly speaking, it is not Scripture which is self-interpreting, but God who as Word interprets himself through the Spirit’s work.” Webster, Holy Scripture, p. 94. In the triune economy of salvation, readers of Scripture enter into the Spirit’s work – which is God’s own “self-interpreting” of God’s incarnate Word. The Spirit does not need our advice or input to speak God’s Word.
Is it wrong to believe in the Protestant idea of the clarity of Scripture? No. But it is better, I think, to constructively move beyond its original articulation by following Billings’ and Webster’s suggestions of grounding clarity in the nexus of our participation with the living, eternal Word of God by the Holy Spirit’s spiration as He illumines, from glory to glory, our relationship and knowledge of God and His Word in ever increasing ways as we are moving toward the reality and consummate form of the once and for all faith delivered to the saints. In other words, it is best to think of Scripture’s clarity as grounded in Jesus Christ, and understand that Scripture’s role is as an instrument or spectacles to allow us to look beyond it to its dynamic and ineffable reality who is, indeed, Jesus Christ. So clarity, by implication, then, should not suggest to us that we have come to possess something by understanding certain things about Scripture; instead the clarity of Scripture should make clear to us that we are now possessed by the One who ever anew and afresh gives Himself continuously to us by the Holy Spirit’s recreative work in our lives as we live from His, from Christ’s life for us.
 J. Todd Billings, The Word Of God For The People Of God: an entryway to the theological interpretation of scripture (Grand Rapids, Michigan: William B. Eerdmans Publishing Company, 2010), 142-43, n. 43.