Karl Marx wanted to dedicate his Das Kaptita1 to Darwin. Marx believed that Darwin’s book contained the basic view of “class struggle in History.” He read Darwin while in prison in December of 1860. “Defending Darwin is nothing new for socialists. The socialist movement recognized Darwinism as an important element in its general world outlook right from the start. When Darwin published his Origin of Species in 1859, Karl Marx wrote a letter to Frederick Engels in which he said, ‘… this is the book which contains the basis in natural history for our view.’
Conner, Cliff, “Evolution vs. Creationism: In Defense of Scientific Thinking,” International Socialist Review (Monthly Magazine Supplement to the Militant) (November 1980)

Joseph Stalin carried out the bloodiest massacres in world history by ordering the execution of 20 million people. He believed adamantly that the teaching of evolution would turn one against God and once God was removed, the people would be committed to the state. Pro-Stalin propaganda published in Moscow in 1940 illustrates this:
“I’ll lend you a book to read; it will show you that the world and all living things are quite different from what you imagine, and all this talk about God is sheer nonsense,’ Joseph [Stalin] said. “`What book is that?’ I enquired. “`Darwin. You must read it,’ Joseph impressed on me” E. Yaroslavsky, Landmarks in the Life of Stalin (Moscow: Foreign Languages Publishing house, 1940), pp. 8-12.

Every time a connection is made between Darwin and communism, the secular world cries foul. They become indignant that someone has dared to make this connection. The same protest is made when the Theory of Evolution is associated with the Holocaust. Even though the connections between these two groups, the purges of communism and the final solution of fascism are irrefutable, evolution scientists and secular humanist professors refuse to admit this connection publicly and the protest vehemently any time this connection is made.