Even in works of fiction, Fyodor Dostoevsky’s Crime and Punishment highlights the barbarity humans are capable of. The protagonist in the novel, Raskolnikov, has a glass of vodka, but he’s not used to drinking alcohol. He then staggers to a park and immediately goes to sleep. He dreams that he is back in his childhood, aged seven, and as he is walking with his father, he sees a drunk trying to make his old horse pull a wagon full of people. When the crowd laugh at him struggling, the drunk peasant becomes furious and begins beating the horse so brutally that the others begin to do likewise by using crowbars and iron shafts. The old horse at first tries to resist, but soon it falls down dead. The boy in the dream, devastated and in great sorrow, throws his arms around the horse and kisses it. All through the dream the owner of the horse is shouting that he can do what he wants with the mare because he owns her.
One would have to have a heart of freezing steel to not be deeply saddened by this poignant passage of human savagery, despite it being fiction. Anyone who hurts a human or animal for fun or pleasure is a degenerate psychopath. But wait a minute: there is no psychopathy or degeneracy if the universe is made entirely of determined matter. All we are left with are chunks of atoms bumping into one another. And, on Naturalism, some of these chunks end up shattering other molecules in motion in the chaotic maelstrom of the material universe spinning ultimately into oblivion: the final heat death of the cosmos. In such a hellhole, there is no creator to save us—and no objective morals or values!
Better: If you watch any debate between a Christian philosopher versus an atheist, the biggest blind-spot on the part of the latter is the Moral Argument. The atheists’ concept of objective morality is either seriously impoverished or they purposely fudge the issue to win an argument, as well as piggy-back on Christian ethics. This surprises most theists, as the cosmic creation argument would seem more prone to secular disagreement. But laying out the significance of objective moral values and duties is like explaining epiphenomenalism (mind is brain, physical without a soul) to a dead horse. More.
What naturalists in fact do, once they govern, is set up masses of rules that are irrelevant to traditional ethics. It is legal to kill a live, viable baby by dismemberment but not to relocate a nuisance urban racoon.
See also: But does it matter anymore whether science makes sense?
Books of interest: “Without God, we would be nothing more than evolved slime fighting for survival”