I am concerned about this equivocation of the term "interpretation" that you keep invoking. In one sense, you address the Reformer's hermeneutical principle of "Scripture interpreting Scripture" which is nothing more than the subsequent Scriptural references clarifying the former (think of how Daniel's "Son of Man" is explained in the Gospel's portrayal of Jesus as the Son of Man). In another sense interpretation is more generic, the usage I employ, to explain how a text's meaning is ascertained. What I would like to know is what do you mean by "Mr. Guthrie thinks Mr. Guthrie is that final authority" in that sense of interpretation? And how do you know if a doctrine is accurately interpreted?