Whose Understanding?

So I'm reading about various medieval approaches to the relationship between faith and reason for a class on the history of Christian thought, and I stumble upon an oddly familiar statement from Anselm of Canterbury. Developing the Augustinian method of "faith seeking understanding," Anselm wrote that "The correct order is to believe the deep things of the Christian faith before undertaking to discuss them by reason" (Cur Dues Homo 1.2, emphasis mine). This method should be relatively unproblematic for those who recognize only one authority for understanding the truth (e.g. the Catholic church). But for a Protestant like myself, who has heard Anselm's method echoed by teachers with radically divergent interpretations of the "deep things" of the faith, the question naturally presses: Whose understanding? Which authority should I accept before applying reason? Moreover, how does this epistemology cohere with Paul's admonition in 1 Thessalonians 5:21, or with the example of the Bereans in Acts 17:10-12?

What do you think? Is there a list of nonnegotiables for you, things that must be accepted by faith without reason? Or do you see the relationship between faith and reason differently?