What I said about Abraham and Isaac yesterday is so close to Kant's view of the matter that I could be accused of repackaging Kant's ideas without attribution. When I wrote the post, though, I had forgotten the Kant passage. So let me reproduce it now. It is from The Conflict of the Faculties (1798), the last book Kant published before his death in 1804 except for his lectures on anthropology:
. . . if God should really speak to man, man could still never know that it was God speaking. It is quite impossible for man to apprehend the infinite by his senses, distinguish it from sensible beings, and recognize it as such. But in some cases man can be sure that the voice he hears is not God's; for if the voice commands him to do something contrary to the moral law, then no matter how majestic the apparition may be, and no matter how it may seem to surpass the whole of nature, he must consider it an illusion. (115)
A footnote to this paragraph reads:
We can use, as an example, the myth of the sacrifice that Abraham was going to make by butchering and burning his only son at God's command (the poor child, without knowing it, even brought the wood for the fire). Abraham should have replied to this supposedly divine voice: "That I ought not kill my good son is quite certain. But that you, this apparition, are God — of that I am not certain, and never can be, not even is [read: if] this voice rings down to me from (visible) heaven." (115)
Here is what I wrote yesterday:
Which is more certain, that I should not kill my innocent son, or that God exists, has commanded me to kill my son, and that I must obey this command? That I must not kill my innocent son is a deliverance of our ordinary moral sense. But wouldn't a command from the supreme moral authority in the universe trump a deliverance of our ordinary moral sense? Presumably it would — but only if the putative divine command were truly a divine command. How would one know that it is?
Kant's argument, put as concisely as possible, is that:
1. It is certain that one ought not kill one's innocent son.
2. It is not certain that a seemingly divine command to kill one's innocent son is truly a divine command.
Therefore
3. One ought to trust one's moral sense and not the putative divine revelation.
Therefore
4. ". . . if it [a scriptural text] contains statements that contradict practical reason, it must be interpreted in the interests of practical reason." (65)
Whether or not one accepts this argument that I am attributing to Kant — you are invited to note that I cobbled it together from disparate passages — you must, if you are rational, see that there is a problem here, one that cannot be ignored, namely, the problem of adjudicating between putative personal and Biblical revelation, on the one hand, and (practical) reason on the other. Something has to give. My judgment is that Kant is right in the passage just quoted, and that our sense of the moral law trumps any contra-moral personal revelation (e.g. a voice commanding an immoral act) and also any Bible passage that seems to endorse the acquiescence in a personal revelation that commands an immoral act.
But why not the other way around? Why not say that the Bible passage trumps our sense of the moral law? The short answer is that our sense of the moral law has superior epistemic credentials. If we know anything about morality, we know that we ought not kill our innocent children. If we don't know that, then we don't know anything about morality. But a voice commanding one to kill an innocent child has no claim on our belief.
Infirm as reason is, it is yet a divine spark within us, an element in the imago Dei. Insofar forth, it is inviolable.