Somewhere in Eastern Europe, an SS officer watched languidly, his machine gun cradled, as an elderly and bearded Hasidic Jew laboriously dug what he knew to be his grave. Standing up straight, he addressed his executioner. "God is watching what you are doing," he said. And then he was shot dead.

What Hitler did not believe, and what Stalin did not believe, and what Mao did not believe, and what the SS did not believe, and what the Gestapo did not believe, and what the NKVD did not believe, and what the commissars, functionaries, swaggering executioners, Nazi doctors, Communist Party theoreticians, intellectuals, Brown Shirts, Blackshirts, Gauleiters, and a thousand party hacks did not believe, was that God was watching what they were doing.

And as far as we can tell, very few of those carrying out the horrors of the twentieth century worried overmuch that God was watching what they were doing either.