Darwin wrote a letter declining the dedication of an unnamed book on atheism, but he wrote it to Edward Aveling. Aveling's common-law wife was Elanor Marx, Karl's daughter, and she inherited his papers. They got mixed up with Karl Marx's papers, and the letter was assumed to have been to Marx. This view found ideological favor in Russia, so it was widely repeated. Later, a letter from Aveling, requesting permission to dedicate his book The Student's Darwin to Darwin, was found among Darwin's papers. Darwin declined permission and argued that science should not address religious matters directly (Colp 1982; Carter 2000).

Darwin did have a copy of Das Kapital, but its pages were unseparated when he died, so he never read it.

None of this matters to the science of evolution.

This is a PRATT. There are more here. I don't suppose it occurred to you to check the validity of any of these claims.

Evolution isn't responsible for World War 1 or 2 or eugenics either. Do we need to discuss?