Per the reasoning of many Christians (not all, but many), it would seem that atheists should murder, plunder, and steal at will, yet such has never been the case as a general rule. Granted, there are Atheists who do harm to their fellow human being, yet I am unaware of any evidence that they do so more than any other demographic representatives of the human race.
Now, my observation regarding such is that people seem to be naturally equipped to know how to treat each other kindly, courteously, and decently; although some admittedly choose to do otherwise. Yet in a collective sense, as in any given society, most people have figured out a way to do so in a civilized manner. Furthermore, in these societies, those who choose to live otherwise almost always represent extreme exceptions to the general practices of the society so represented. (This is one of the reasons I attempt to avoid grouping and classifying various religions and or cultures based upon the doings of extremists within their respective ideology. For those who practice violence are almost always the extreme exception to the general lifestyle of the overall majority within any respective group/culture. This was true of even Nazi Germany, and I don’t doubt this rings true for most any society one could consider)
Now, in light of the various and differing religions, ideologies, cultural distinctions, economic theories, social theories, and political ideologies ever present in any and every culture which has or ever will exist, the fact that most people within any such respective culture figure out a way to live together in peace and harmony, leads me to conclude that separate from each respective cultural ideology of all societies of all time, there seem to be qualities of humanness which are universal to our species, which serve as a foundation for peaceful and harmonious relationships.
Such as they are, these are my thoughts on the matter of individuals, civilizations and morality.