I am often told, when arguing about religious beliefs, that without religion one cannot have moral justice. One cannot call Hitler immoral if one has no "objective" standards of morality. But Hitler, along with Pope Urban II, who authorized the crusades, and Osama bin Ladin, who was responsible for the deaths of 2,947 on September 11th, 2001, believed that he was doing the right thing, and the moral thing, and the thing which would lead him to paradise. In fact, all three of these men believed this because of a religious book which claimed objective moral teaching. There is nothing particularly malicious in the bible itself, of course, but rather in the fact that moral beliefs are dictated or taught, rather than carefully meditated on and chosen. I hope the following will be a decent response to both problems, that of defining morality within the confines of atheism, and that of creating a code of morality which may be truly objective because of its room for subjectivity.
There can be no gods. The existence of a god dilutes the perfect purity of the ideal religion, which is no religion at all but rather a pure moral code. If we choose to do something because of what our god's interpreter (a religious leader) has told us, we must accept the possibility that this interpreter has mistook or lied about the most moral course. The basic element of morality is suffering and happiness. The solution to any moral dilemma is then, in theory at least, to think what the effects of each choice will be for those involved: which will cause the most happiness and the least suffering. Each human being must independently decide for him or herself what to weigh in the balance. For example, do humans count as much as other animals? Is a fly, with no nerves or brain to speak of, as important as a mammal which can feel real pain? Is a child or some other helpless person more important, on the grounds that, left to their own devices, they would not do the right thing for themselves? What about a human fetus? Or someone who is guilty of a heinous crime? There is no universal truth in any of this. Every human being must decide the answers for him or herself.
To me the answer to each of these questions is clear, and I use those answers in my everyday life to determine my opinion on the moral problems facing us today. For example, abortion, on which I hold the typical left-wing view. I challenge anyone who claims to be pro-life to answer this question: is the life of a living being with less brain cells than a fly, whose life as an unwanted child will almost certainly be painful, more important then the lifestyle of a young woman who has inadvertently become pregnant.
Through these decisions one can form a system of morality independent of dogma.