Testamental Hermeneutics

In his excellent Infant Baptism and the Covenant of Grace, by far the best articulation of a covenantal argument for believer baptism that I've yet come across, Paul K. Jewett outlines what he believes to be a serious hermeneutical error into which Reformed paedobaptists fall into. This error, in a nutshell, is that they fail to take sufficient account of the differences between the Old and New Covenants--or, more accurately, the Old and New administrations of the one everlasting covenant of grace--that arise out of the fulfillment and spiritualization of the covenant in Christ, and the extension of the covenant to the Gentiles with the establishment of the church. In this mode of thinking, the Paedobaptist Christianizes Old Testament Israel, focusing on the spiritual aspect of the covenant and its sign to the exclusion of the temporal, physical aspects of God's covenant with Israel. The Paedobaptist also, in some ways, Judaizes the New Testament Church, applying the Old Testament promise of a fleshly seed and deriving a concept of "covenant children." The Paedobaptist's hermeneutical structure causes him to read the Old Testament as though it were the New Testament (and vice versa), rather than properly reading the Old in lightof the new.

In a recent blog post, Douglas Wilson posts several points of a "Primer on Eschatology." Laying out some fundamentals of the postmillenial view (to which he subscribes), he describes preterism, the view that "Many of the prophecies of the Bible which premillennialists consider unfulfilled, postmillennialists believe have already been fulfilled." He says that we must look to the New Testament as a sort of "divine commentary" on the Old, telling us which Old Testament prophecies have already been fulfilled. As an example, he cites Isaiah 11:8-10 and Paul's commentary on the passage in Romans 15:8-12 and 15:15-18, about which he notes, "Paul places the fulfillment of Isaiah's prophecy squarely in the context of his mission and ministry to the Gentiles of the first century world. If the New Testament tells us that this is what Isaiah means, then this is what Isaiah means."

Now. As a general principle, we must always be careful to let Scripture interpret Scripture, trying as much as possible not to bring presuppositions or pre-conceived notions to the table when we seek to understand Scripture. However, I wonder if Wilson is perhaps exercising the same flawed hermeneutic in relation to eschatology that he does in relation to baptism and the Covenant (having read his To a Thousand Generations on infant baptism, I can say with some confidence that he thinks like the subject of Jewett's criticism). Is he reading the Old Testament in light of the New Testament, or as though it were the New Testament? Wilson contrasts his essentially literal, preterist understanding of New Testament passages about the end times being "now" or "soon," wherein one says that "the writers of the New Testament expected to see these things come to pass in their day, and that they were correct" with the view that "spiritualizes" the apostles' words and understand them as indicating that the end of times is unknown and to be expected at any time, rather than literally-temporally "soon." If Wilson (et al.) fail properly to understand the "spiritualization" of the covenant with regard to baptism, could not his cracked hermeneutical glasses also cause him to overlook the spiritual nature of New Testament end-times-related passages?

I confess I am not as skillful or practiced as Jewett in wielding the hermeneutical scalpel, so I can't adequately say whether I'm onto something here or trying to serve soup with a fork. I hope I'm wrong about Wilson, because postmillennialism is attractive and I'd like to believe it if it's Scripturally warranted.