In reply to Curmudgeon:
Can an atheist act in moral and ethical ways? Certainly, they can. All humans still retain the image of God upon them, even after the fall of Adam and Eve into sin. The image of God was effaced at the fall, but it was not erased, and so man still understands right and wrong no matter how many try to say otherwise.
The difference between the atheist and the Christian in this sense is that the atheist may act ethically for certain reasons, but he has no ultimate reason for acting ethically because there is no ultimate moral authority that exists over each sphere of his life. Without this ultimate authority, each atheist defines morality on his own terms, although his morality is influenced by the remnants of morality from the image of God within, along with the strictures and constraints of the culture and society in which the atheist exists.
The Christian, on the other hand, acts morally out of the knowledge of the moral law given by God in His Word and a love for the Law-giver Himself.
When confronted with a situation that demands both the Christian and the atheist to make moral choices, a situation in which societal constraints are removed, the reaction of each will be vastly different. If a society deems it morally acceptable to kill unborn babies, for instance, the atheist sees no reason to oppose the practice. His own “moral law” even tells him it’s the compassionate thing to do in cases where the child is the result of rape or incest. The Christian, however, knows abortion is wrong because his moral choices are built upon the moral Law-giver who has declared all human life to be sacred because it is created in the image of God. The Law-giver has proclaimed, “You shall not murder” (Exodus 20:13) and, for the Christian, there’s the end of it.
So can an atheist act ethically? Certainly, but he has no ultimate reason to do so and no ultimate authority to look to in order to ensure his line is indeed straight and unbendable.
**And one other point. As a Christian, I know unbelievers who are "nicer" people than some other Christians I know(who may not even be one). It gets me upset, but its the truth. Biblically however, being good isn't the way to salvation. Those Christians need to straighten up and fly right though. I work with unbelievers, not atheists though, that I love to death. Even if they were atheists I'd still love em'.