Our brains are fallen and untrustworthy, which ought to be evident by the fact that few of us can agree completely on anything whatever.
That being the case, God had pity on us and gave us His trustworthy revelation. To trust our fallen brains and distrust His revelation is what dishonors God.
Does His revelation express itself inside of our fallen brains or does it bypass them somehow? I'm sure you can see the problem here. If we can't trust our brains, it seems difficult to know when the revelation is His or ours. The loony bins are full of people we've decided are listening to their fallen brains.