It is not possible to make a simple separation between the creative and destructive elements in anxiety; and for that reason it is not possible to purge moral achievement of sin as easily as moralists imagine. The same action may reveal a creative effort to transcend natural limitations, and a sinful effort to give an unconditioned value to contingent and limited factors in human existence. Man may, in the same moment, be anxious because he has not become what he ought to be; and also anxious lest he cease to be at all. . . .
The statesman is anxious about the order and security of the nation. But he cannot express this anxiety without an admixture of anxiety about his prestige as a ruler, and without assuming unduly that only the kind of order and security which he establishes is adequate for the nation’s health. The philosopher is anxious to arrive at the truth; but he is also anxious to prove that his particular truth is the truth. He is never as completely in possession of the truth as he imagines. That may be the error of being ignorant of one’s ignorance. But it is never simply that. The pretensions of final truth are always partly an effort to obscure a darkly felt consciousness of the limits of human knowledge. Man is afraid to face the problem of his limited knowledge lest he fall into the abyss of meaninglessness. Thus fanaticism is always a partly conscious, partly unconscious, attempt to hide the fact of ignorance and to obscure the problem of scepticism.
Reinhold Niebuhr.The nature and destiny of man. Vol. 1. London: Nisbet, 1941, pp. 196ff.