Of all tyrannies, a tyranny sincerely exercised for the good of its victims may be the most oppressive. It would be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated; but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience.
The Humanitarian Theory of Punishment". "God in the Dock". Book by C. S. Lewis, 1970
Very similar is
Theocracy is the worst of all governments. If we must have a tyrant, a robber baron is far better than an inquisitor. The baron's cruelty may sometimes sleep, his cupidity at some point be sated; and since he dimly knows he is doing wrong he may possibly repent. But the inquisitor who mistakes his own cruelty and lust of power and fear for the voice of Heaven will torment us infinitely because he torments us with the approval of his own conscience and his better impulses appear to him as temptations.
"A Reply to Professor Haldane (1946)". "Of Other Worlds: Essays and Stories". Book by C. S. Lewis, 1966.