Morality

[Brian37]

No, he’s referring to the effort to see The Good. And by this he doesn’t mean, that it takes such effort to see what’s right, but  the ultimate root, or source of such perception. Our perception of what’s right, is like seeing light from the sun, but not the sun itself, it takes considerable effort to see the sun.

“. It cannot be clearly seen or explained, but once it is recognized, it is the form that allows one to realize all the other forms.”

So, if you accept Plato's bit of wisdom here, then you may want to rethink the idea that only theists can be moral realists. 

Atheists can recognize the Good as well as any believer can. Some things might even work in the atheist's favor in trying to recognize the Good, such as not being bewildered by dogma. An atheist can search for the Good armed with only a sincere heart and mind. At the very least, I will say that an atheist is at no disadvantage when trying to distinguish the good from the not good. At the very least, they are just as able to distinguish an objective morality as a believer.

I really wouldn't try to argue "atheist" are better. "Off" is a mere position. It does not denote a moral code, or a class, political view, or economic view.

The real argument to be made is that when better data comes in, you adapt that data and scrap the older bad data.

FYI Plato did not get everything right himself. Plato got the idea of questioning right, but he still did not have benefit of modern scientific method. If you read the preface to "The Greatest Show On Earth" by Richard Dawkins, in it he explains, much of humanity's chase for a utopia infected religious and political thinking with his idea of "Essence". The idea for Plato was that if you simply thought about something long enough you could find that perfect thing.  IE, "essence of rabbit" or "essence of chair". Unfortunately that idea of the perfect thing bled into religious and political thought.

I would say that humanity would do better without old mythology. I don't mean erasing history, we should not do that. But we should learn from our mistakes as a species and leave bad claims behind.

If all 7 billion humans were suddenly atheists, we would still have our differences and groups and conflicts. Our species behaviors are not in a label, but in our evolution.