Was Christianity at fault for the burning of supposed witches?
I say no. Just like I say no to the other things. Flawed human beings, in their quest for power and control, subvert and pervert theories and belief systems to their advantage. There is nothing in Marx’s writings that supports the gulag, nor is there anything in Darwin’s writings that support the ethnic cleansing (read: wanton murder) of Jews. Flawed humans, again, in their quest for power and control instituted those things on their own.
I believe that the events of the 20th century that you attribute to the biological theory of Charles Darwin would have happened regardless.
Evolution made the Bible into fairy tales and the rejection of God’s principals mainstream. It gives despots me more cover than they’ve had in a long time (when they could claim divinity). People not fearing God is why they burned witches and why the murdered Jews. Evolution has been great for Satan because of it’s mass appeal. We can’t all claim to be gods. Now from least to greatest, we can murder in the name of perfecting our species.