Originally posted by kingdanwa
Why not call acting selflessly Evil and its opposite good?
To an atheist, the worst possible thing is a shortened life, because there is nothing before or after this short existence. Therefore, life is good for an atheist. For believers of every faith that I have come into direct contact with, life is a neutral to good thing, and the taking of life is generally an evil thing (there are always qualifiers).
To act selflessly is to support life on the broadest scale, and therefore would do the most positive thing possible for either of the above sets of people. For atheists, this is helping the greatest number of people live the longest amount of time. For theists, it is following the mandates of their faith.
To act selfishly, on the other hand, is generally destructive (or at least irreverent) to life. This is clearly a negative to anyone who values life, which is something even more precious to the atheist than to the theist, for there is no afterlife. Thus, the one time alone counts.
The primary difference is that the atheist believes that any action that causes no harm cannot be negative, while theists hold that their god will punish them even for actions that bring no one harm (lust, for example, if not acted on is often still negative).