Paintings of Adolf Hitler could be found in a portion of hell built by evil humans.
The Doom Marine found a secret level. That looked to be built by humans, rather than demons. He wondered who the inmates of that corner of hell would actually be. Inside he discovered Wolfenstein SS (Nazi schutzstaffel).
In the Doom Novels the doom aliens and demons are often compared to the Nazis and Hitler.
The demons from the River Styx had appropriated the crooked cross" that a certain Austrian corporal had appropriated in the middle of last century.
The most important lesson from what Hitler did to the Jews, was that at the end of the war, they were still in the world. It was a testing, one they passed by surviving when the 'Thousand Year Reich' was destroyed. If they'd been destroyed, it would have been a judgment.
Hitler and Stalin promised peaceful occupation and promised each collaborator that his own government would be given the top command slot. A tried and true approach. Naturally, they screwed the traitors, killing hundreds of millions.
When they were fighting Hitler, the allies used to say that the other side was so terrible that the allies should forgive their own shortcomings.
Bureaucracy was a book by Ludwig von Mises. He wrote about freedom when the only threat to it was other human beings. He said capitalism is good because it 'automatically values every man according to the services he renders to ... his fellow men.' " He was no friend of socialism. The book was written during World War II. Where he used Hitler and Stalin as his two perfect models of socialism in practice.
Behind the scenes
A possible reference to the Wolfenstein and Doom Wolfenstein levels appears in the Knee Deep in the Dead novel. When Flynn and Arlene discuss possiblity of encountering giant vampire slugs from the planet Pornos, or being machine- gunned to death by Nazi schutzstaffel.