David Basinger, Journal of the Evangelical Theological Society 24:3 (1981), pp. 233-38.
Theists frequently argue that nontheists must affirm the following: (1) If there is no God, each person must define "good" and "evil" for herself. (2) If each person must define "good" and "evil" for herself, there can be no objective moral standard. (3) God does not exist. (4) Therefore there can be no objective moral standard (i.e., all moral principles are relative). Some nontheists agree (e.g., Sartre) and attempt to live with the implications of (4). Others deny (2), claiming that the existence of an objective moral standard is not dependent on religious commitment. Kai Nielsen is one of the best known and most outspoken members of this group. Nielsen argued that "the nonexistence of God does not preclude the possibility of there being an objective standard on which to base [moral] judgments."
Kai Nielsen on Ethical Certainty said...
Ethics without God, rev. ed. (Prometheus Books: 1990), 10-11.
It is more reasonable to believe such elemental things [as wife-beating and child abuse] to be evil than to believe any skeptical theory that tells us we cannot know or reasonably believe any of these things to be evil... I firmly believe that this is bedrock and right and that anyone who does not believe it cannot have probed deeply enough into the grounds of his moral beliefs.
First Knight, Lorne Cameron and David Hoselton, writers (Columbia Pictures: 1995) 00:56:26 mark.
You know the law we live by. And where is it written beyond Camelot live lesser people, people too weak to protect themselves, let them die? Malagant: Other people live by other laws, Arthur. Or is the law of Camelot to rule the entire world. King Arthur: There are laws that enslave men, and laws that set them free. Either what we hold to be right and good and true is right and good and true for all mankind, under God, or we're just another robber tribe. Malagant: Your words are talking you out of peace and into war. King Arthur: There's a peace you only find after war. If that battle must come. I will fight it!