Your presupposition is that Hitler misinterpreted Darwinian theory. He understood it all too well. He understood genetic changes, over time, with survival of the fittest yielded an evolved species. He sought to bring about the Ubermenschen (Aryian supermen) and do away with those stipulated by Hitlers scientists as Untermenschen (subhumans, so stipulated by Hitlers scientists). Hitlers problem was that he needed to increase the rate of genetic changes. He did this by instituting laws not allowing certain portions of the population to engage in business. The Darwinist movement, as developed by Ernst Haeckel and twentieth century German intellectual history served as a prelude to Nazism. As the theory of Evolution caught hold it took a firm grip more than any other place in the world at that time.
Hitler first set up an infrastructure to stop the subhuman (his term) from breeding. FIrst he killed the defective infant (according to Darwin it would eventually happen anyway), then removed the cripples and syphillitics of older age, spin bifid a patients, Downs Syndrom, Turner's Syndrome Patients, he propagated abortion, and implemented the program of Lebensborn (selective breeding of 'better' Nazis). Then of course he implemented the 'work camps', the death camps', Medical experimental camps, as well as propaganda machines, all of which were geared to implement the destruction of Jews, Gypsies, Poles, Negroes, Slaves ( all stipulated by the German intelligence as inferior). This allowed Hitler to 'speed up' death of the 'inferior' and speed up the natural selection of supermen by selective breeding.
Now as far as you ascribing the term "evil" to anything, I must wonder, how you, as a proponent of Darwinism can see evil as a metaphysical possibility. If it evolved, in accordance with Darwinism or neoDarwinism, evil cannot exist. It just ….is. Why would a mindless, purposeless, random universe be referred to as evolving evil? Or perhaps you do believe in Moral Law. If so how does a purposeless universe give rise to Moral Law? If not, what standard do you use to determine, say evil, from good?
If you're going to sustain the claim that Hitler didn't misinterpret Darwin, you'll need to provide some evidence that Darwin advocated the extermination of racial groups to enhance human purity.
If not, what standard do you use to determine, say evil, from good?
I use a very simple concept called the Golden Rule. I think your answer to that question would be more interesting given that Biblical morality (ironically) is and has been an evolving concept. Biblical attitudes to everything from rape, slavery, genocide, the treatment of prisoners, women's rights etc., etc have changed radically over years.