How blind are we?

Thus it is possible to over-estimate, as well as to under-estimate, the blinding of the intellect by sin. We have indeed no right to assert, as some pessimists do, that sinful man as such, cannot know anything aright. This kind of pessimism is out of touch both with the Bible and with experience. On the other hand, an optimism which ignores or denies the significance of sin is equally unjustified. In the one case, as well as in the other, an undifferentiated general statement is wrong. Rather, it is necessary to make a distinction between knowledge of the world and knowledge of God. Sin does not hinder men from knowing the things of the world, the laws of nature, the facts of nature, and man in his natural, historical and cultural manifestations. But the more we are dealing with the inner nature of man, with his attitude to God, and the way in which he is determined by God, it is evident that this sinful illusion becomes increasingly dominant. The more closely a subject is related to man's inward life, the more natural human knowledge is “infected” by sin; while the further away it is, the less will be its effect.—Emil Brunner, The Christian Doctrine of Creation and Redemption, 27