Into the Wardrobe

There's a powerful passage by Lewis in one of his essays, and I am wondering if one of you Lewis scholars can help me track it down!

Lewis is talking about the tremendous danger in theocracy. He says specifically that its greatest danger is that the cruel man of God comes to see his wickednesses as virtues and pleas for mercy or kindness as wicked temptations to be overcome.

My guess is that Lewis had in mind say the priests who oversaw the Spanish Inquisition's tortures -- though of course the insight has far greater generality.

Can anyone help me out? There's several places where he talks about the dangers of theocracy but only one with the specific insight I mention above.

OK, I'm an idiot. Just found it. It's from "Reflections on the Psalms", chapter 3.

"I am a democrat because I believe that no man or group of men is good enough to be trusted with uncontrolled power over others. And the higher the pretensions of such power, the more dangerous I think it both to rulers and to the subjects. Hence 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 may 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 more because he torments us with the approval of his own conscience and his better impulses appear to him as temptations."