IMO, the principle error of NPP is the negligence it pays to the biblical historical context. Instead of using the infallible and inerrant historical context as narrated in the Bible, it uses the fallible and errant empirically-derived (and thus logically fallacious) "findings" of contemporary historical research to re-interpret the message of Scripture. After all, why do you think that there is so much narrative found in the Scriptures?
It is a pity that Dave did not pick up on this vital point in his evaluation of NPP. Attack the entire fallacious enterprise of empiricism (which is a form of unbelief), and the whole enterprise of NPP will come crashing down.
Where P = Empirically-derived findings are [thus] logically fallacious.