Whether they are Nazis, or slaveholders, or abortionists, or Supreme Court "justices," they just can't get around the self-evident fact that it is morally wrong to murder or enslave innocent people. Which explains why they are compelled to to dehumanize, to depersonalize, their victims, who are self-evidently created in the image and likeness of God.
A human being is intrinsically a human being, and it is wrong to enslave or murder them, no matter how many Nazis, or slaveholders, or abortionists try to pretend otherwise.