Religious authority comes in a wide variety of forms. There’s certainly something to be said for a propositional authority, if one might call it that: in short, a Magisterium. I realize that, as a Roman Catholic, this is your personal preference, and that the admitted messiness of Orthodoxy, with its various “jurisdictional” distinctions and overlaps—to say nothing of the multiple schools of law in Islam—leaves you unsatisfied, if not aghast!
It’s worth asking, however, whether God is quite so tidy in this respect as you may think. Propositions, beginning with those in the Bible itself and moving through creeds and papal bulls, can give the illusion of a security that’s not really there, because of course it finally can’t be there, in the face of an apophatically “incomprehensible God”.
I’m reminded—as is so often the case!—of a passage from C. S. Lewis. It appears in a chapter called “Scripture” in his book Reflections on the Psalms. He’s talking about the merely “human material” (including outright error) that’s undeniably to be found in the Bible, and of the ways in which God is nonetheless able to form it, messy though it is, in the working out of His revelation:
“To a human mind this sublimation (incomplete) of human material, seems, no doubt, an untidy and leaky vehicle. We might have expected, we may think we should have preferred, an unrefracted light giving us ultimate truth in systematic form—something we could have tabulated and memorized and relied on like the multiplication table. One can respect, and at moments envy, both the Fundamentalist’s view of the Bible and the Roman Catholic’s view of the Church. But there is one argument which we should beware of using for either position: God must have done what is best, this is best, therefore God has done this. For we are mortals and do not know what is best for us, and it is dangerous to prescribe what God must have done—especially when we cannot, for the life of us, see that He has after all done it.”
I’m reminded too of the Koranic verse: “Had God willed He could have made you one community. But that He may try you by that which He hath given you (He hath made you as ye are). So vie one with another in good works. Unto God ye will all return, and He will then inform you of that wherein ye differ” (5:48), and of this hadith of the Prophet Muhammad: “The divergence of opinion among my companions is a mercy.”