Darwin was also a devout Christian, even after he wrote
Orgin of Species but this is not often mentioned either.
Darwin has been used to push one political ideology or another.
My understanding is that Darwin's wife was a devout Christian, Darwin was not. His wife tried to convert him. She did not want to spend her eternal afterlife without him. He loved her greatly and he did not want to disappoint her. Still, as much as this bothered him he was unable to become a devout Christian.
This should have little bearing on the validity of his work though. He was a brilliant man, and also by definition a deadly warmaker. He was the genetic product of many thousands of years of brutal war, as are you and me.