The problem is exacerbated by those proponents of revealed religion who exclude at the outset any use of natural reason as a means of testing allegedly revealed scriptures. The dominant school of theology in Sunni Islam, the Asharite school, asserts that “the mind is unable to know the mind of Allah … except by means of His messengers and inspired books….The good is not what reason considers good, nor the bad what reason considers bad….The measure of good and bad…is the Sacred Law, not reason.” The Christian Protestant theologian John Calvin urges human beings “to renounce their reason, their carnal desires, and themselves entirely, that they may be brought into obedience to God alone…” These writers suggest that human reason is simply too weak and fallible to be used to test or evaluate the infallible word of God Almighty. Calvin also seems to suggest that relying on one’s own reason is impious, since it is incompatible with absolute obedience to God alone.
The Asharite and Calvinist approaches strike me as very dubious and even dangerous. To renounce our own reason because it is fallible is simply incoherent: fallible as it is, it is all we have, and we have no choice but to use it to distinguish plausible from implausible claims, whether those claims are allegedly revealed or not. The Asharites and Calvinists surely use their own reason to make some initial assessment of whether the Bible is more likely to emanate from God than the Koran, or vice-versa. They may claim that God is doing all the work for them – illuminating their minds and moving their wills with his grace – but this is a retrospective explanation of what seems like a clear instance of individuals doing something, namely, inquiring, thinking, assessing and reasoning. Moreover, it is morally dangerous and irresponsible to abandon one’s natural sense of right and wrong on the grounds that “God knows better” and has revealed things that seem immoral from the standpoint of natural reason. This opens the path to the worst sorts of fanaticism, intolerance, and religious violence. If an alleged body of revealed scripture contains teachings that your conscience tells you are manifestly immoral, that in itself is a good reason for rejecting the claim that the writings represent God’s will.
But now we have a new problem. If revelation must be tested by reason before it is believed, we run the risk of making revelation superfluous. If I should only believe what my reason can confirm independently of revelation, then why consult revelation at all? Why not just stick with “religion within the bounds of reason alone,” to borrow a phrase from Immanuel Kant? We seem to be caught on the horns of a dilemma: either we abandon our reason and make a blind leap of faith, or we rely on our reason and reject the very idea of revealed religion.
But maybe there is a third possibility. Maybe we can insist that revelation must be rational at least in the sense of not violating what we know naturally (logic, science, morality), while being open to the possibility of learning things from revelation that we could not discover by unaided reason alone. After all, if God is the transcendent creator of everything and stands outside of the created order, then God is utterly different from the creatures within that order. It stands to reason that God is above and outside of our concepts and categories and may have things to tell us that reason alone could not discover. If reason and revelation flow from the same God, they must both be reliable sources of truth about God and they cannot contradict each other. They may partly overlap, but they may also complement each other without completely overlapping: that is, one could tell us things that the other does not, without the two clashing in any fundamental way. Perhaps it is reasonable to be open to the possibility of truths that reason alone could never know.