No God means no right and wrong in any form. If there is no higher authority that established our moral laws, then that would mean that they are all man-made. All our moral norms, then, would be arbitrary. Even good moral codes would have no true authority backing them, because there is no reason to follow another man's ethics when you are just as capable of making your own. Every pro-life argument stems from the principle that human life has an inherent dignity and that killing an innocent person is wrong. If that principle was just agreed to by people, rather than imposed by a higher power, then it could just as easily be abolished by other people.