“Anathema to the Christian who will not be certain of what he is supposed to believe, and who does not comprehend it. How can he believe that which he doubts?”
– Martin Luther, “De Servo Arbitrio” (“The Bondage of the Will”)
In 1524, the great humanist Erasmus of Rotterdam published his defense of Catholicism against Martin Luther, “De Libero Arbitrio” (“Of Free Will”). Part of it was kind of a scorched earth defense. Erasmus argued that there was so much in scripture that is hard to puzzle out, and he pointed out that theologians had been arguing about doctrine for centuries without any semblance of an end. Since we can’t know with any certainty, we should just accept the traditional teachings of the church.
Luther was not impressed. He completely rejected Erasmus’ skepticism. Part of his response was a retreat to subjectivity: we know what our conscience compels us to believe from the reading of scripture:
The Holy Spirit is not a Sceptic, nor are what he has written on our hearts doubts or opinions, but assertions more certain, and more firm, than life itself and all human experience.
I think this argument is still going on. I see plenty of Protestants who are willing to admit doubt and consider theological arguments. But there are many more who act as if we just know certain key doctrines and there is no room for doubt. I think that may be part of the issue behind the Metaphor or maybe not problem.