Evangelical theology, as well as most conservative theologies, fails because there is no practical way to maintain its underlying exegesis. The hermeneutical method used is generally called the historical-grammatical method. With this method, the meaning of a biblical passage is interpreted based on the historical context and literary characteristics of the passage.It’s more complex than that, but that is a useful working definition.
The problem with the historical-grammatical method is that the New Testament authors did not use it to interpret the Old Testament. The authors used pesher techniques to understand our Old Testament (as well as additional books that Christians do not how to be inspired). Almost every prophecy mentioned in the New Testament has been reinterpreted. The historical-grammatical method of these same Old Testament passages stands in stark contrast. In fact, that method ends up negating most prophecy about the Messiah. And without a Messiah actually being prophesied about, what of the New Testament’s interpretation of Jesus? He is no longer the Messiah and all of the Pauline, Johanine, Lucan, etc. theologies which proceed from this fall apart. Without a pesher interpretation of the Old Testament, there is no valid case for Jesus being the Messiah.
Thus, there are only a few choices: 1) makes exemptions for the pesher interpretations because those were “inspired by God” or 2) find a new hermeneutic that can encompass all of the biblical passages or 3) admit inconsistencies and fallacies by the biblical authors.
The first choice is the preferred for most evangelicals, but it is inconsistent. It’s simply a blind faith choice that has no logical underpinnings. But if God is not a God of confusion and he is the foundation of all logic, this seems contrary to His supposed nature. The second choice seems difficult to ascertain simply because there have been so many hermenuetical and theological systems that have come and gone. They all (well, most) share the same flaw: the assumption that all of the biblical texts form a logical whole. The third option tastes like filth in the mouth of an evangelical. They cannot consider it without having to rethink their entire worldview.
Overall, the historical-grammatical method is the most logical method and the safest to use. It’s just too bad that the biblical authors didn’t know this.