“The fear of the Lord is clean, enduring forever” (Ps 19:9a).
Because it occupies the penultimate spot on Psalm 19’s list of scriptural perfections, we should take “the fear of the Lord,” in this context, as a perfection of Scripture as well. What’s going on?
I take this as an example of naming something by means of the effect it produces (i.e., metonymy). So the claim is that, among its many perfections, Scripture produces the fear of the Lord.
That claim, in turn, I take to be an indirect reference to the holiness of God. So the fuller claim is something like this: Scripture manifests the holiness of God and thereby produces the fear of the Lord in its readers.
If that’s on the right track, then returning to the verse: “The fear of the Lord is clean, enduring forever,” suggests that Scripture, in conveying the holiness of God, and in producing the fear of God, also purifies (“clean”) and bestows everlasting life (“enduring forever”) upon its readers.
Thus, the full claim of Psalm 19:9a is something like this: In conveying the holiness of God, Scripture inspires reverence for God, purifies our thoughts about God, and grants eternal life with God.
This, in short, is what it means to call the Bible Holy Scripture.