IMO, when people start to question whether or not "right" and "wrong" exist as moral absolutes, they are engaging in (among other things) moral relativism (one of those "other things" could be rationalization). "There are no moral absolutes." But then, they've just contradicted themselves by stating one. In other words, there is no such thing as moral relativism.
The physical world has absolutes (eg, conservation of mass, speed of light); the biological world has absolutes (self-preservation); so does the mental-symbolic world (principles of math and logic). It would seem inconsistent to state that there are no moral absolutes.
(Of course, if you believe in a spiritual dimension to reality, then to stay consistent there are spiritual absolutes, in which case there exists - among other things - a "Higher Authority" which establishes what is right and wrong. But, with respect to atheists, we don't have to go there at the moment).
One could argue that moral absolutes (independent of Spiritual Authority) are defined as those by which a society prospers, not just in terms of material wealth (perhaps least of all in material wealth), but in compassion, adaptation, longevity, between its members and with other societies as well as with its physical environment. "Murder is wrong" would be an obvious example. Any society which sanctions murder will bring perhaps short-term material gain, but also eventual extinction. I'm no historian, but I think history does bear this out. Witness most recently the extinction of the Soviet Union, the second most powerful politico-military entity ever to exist.
True, nothing lasts forever. But respect for What Is Not Me brings us closer to that than anything else.
And now, back to our regularly scheduled program...