Also, I don't buy the whole America as a moral nation. I agree that liberal democracy as espoused by our founding fathers was superior to other systems of the time. However the system they espoused extended sufferage to them and their class only - white men with property. (suffrage was not extended to men without property until 1828, women in 1920, and then the civil Rights movement). In short, while their ideas may have been based in the Enlightenment, their actions and the system they built was based upon self interest. Furthermore, I see the "Age of Reason", while certainly a progression, initially began and gained in popularity with the rise of the western European bourgeoisie. It gave them a new paradigm, opposed to the old one of a nobility whose power was based upon religious ideas of entitlement. "Reason", in this sense, gained social power as the espoused moral base of the new proprtied class. The dominant social group of each age always supports a philosophy which justifies and furthers their own power. Then, as conflicts arise within that group power may be extended to other group as alliances are formed. This leads to the evolution of ideals and morality. At times previously subservient groups may revolt and either be ultimately subsumed in a (sometimes newly) dominant faction and their ideals will also be subsumed. Or the revolting group may form a new antithesis which will either become dominant or eventually be subsumed.
Hegelian dialectics, especially dialectic materialism, is the model I have found to be the best at explaining history without resorting to anything other self interest. However I think it works as a modeling paradigm and find that Marxists who claim it leads to a any kind of end state or goal are missing the point.
As for Ayn Rand, I've never read her but I am familiar with her philosophy. I don't think man is at all heroic. I also agree with her in seeing men as primarily selfish beings and I think, at it's base, self interest is the only "real" motivation. However, I also think that man, as a social animal, will form alliances, groups, classes, social structures, etc. And he will model the ideals of his group based upon principles which will allow for the groups progression. This will ultimately lead to the illusion of altruism - which, while an illusion, ultimately means the progress of the largest group. I think Ayn Rand totally missed this. Just because altruism is a fiction, doesn't mean it can't lead to a "greater good". So, yeah, while "rational self-interest" can be a start and at the core, making it the cornerstone of morality and ignoring the "psychology of the social", her "Objectivism" provides no real basis for social good. I mean, no one is more "rationally self-interested" than a despot.
Ok, now I'm really done.

People live and stay alive because they were born and they eat food and drink water. Classifing life as happy or productive is inherently based upon subjective models. Any attempt to generalize a model is sophistry. Just like religion.
Anyway, that's my two cents.

By contextual clues you begin by defining "negative" as "not believe in God, other religions, or the super-natural"

then you assert:

"But one cannot live an entire life based on a negative"

When we replace the word negative:

Your statement reads:

But one cannot live an entire life not to believe in God, other religions, or the super-natural"

This assertion is incorrect. I know productive, good, happy people that were never been deluded into faith based world of superstition
You have no idea how ludicrous I find that assertion.

How does not accepting a claim based on faith defined as a "negative?"
and more importantly, how can you possibly assert that to live an entire life free from the belief in the supernatural or a god . . .

"In order to have a productive, happy existence, one must base his or her existence on some paradigm of the real world."

Half way through that statement (started with a Capitol but the previous statement not ended with a period) you appear to change gears and drive on a completely different road to the completion of your post; that nearly contradicts your opening premise?

Curious that you say agnostics/atheists still have issues with Christianity, to me suggesting it is surprising in some way. Many of us have a great many issues with all religions, and particularly the Abrahamic monotheistic religions as they are appalling. No serious minded non-religious person bases their life on a negative. He or she states the negative that is religion, but looks to the positives in reason and evidence based thinking, and for many of us, also progressive social and economic thinking. Reason is a methodology, but the goal should be fair and just societies. Religion is, and always has been, a blockage to achieving that goal.

The 'sanctity of property' can't stand up against 'eminent domain.'

Also, I've long believed "pursuit of happiness" was poorly phrased. Perhaps if one spent less time pursuing happiness, and decided to just be happy, life could be more groovy.

Also, one nation under Galt would suck ass.

Okay.

What? Raison d’être? Um, no. I don’t believe in Santa, either, but neither are of any import in my life, let alone my reason for existence.

Additionally, you are lumping the two separate definitions of the word ‘reason’ together.

"They do not believe in God, other religions, or the super-natural, and that is their raison d'etre."
I have never heard an atheist say that not believing was their reason to live. Every atheist still believes in the natural world and has to deal with the world as it is and the consequences of their actions. You don't have to choose between such concepts like Reason or Faith all the time. I'm not even sure what it would mean to base someones life on reason. It all sounds a bit naive to me.
I have a problem with someone saying a nation in itself is moral. Does that mean every action that nation makes is moral? One might argue that the principles of the USA are moral, but let's not forget that when it started it was built with the help of slavery. How would a moral nation accept slavery? Rand was just so negatively impacted by the USSR that the USA seemed like paradise to her, apparently. I think she wasn't the brightest person to be honest.

When you assert that most __s believe X; this is also known as the straw man fallacy. Do you really know all you claim to know about other agnostics and atheists? How?
And quoting Ayn Rand is the argument from authority fallacy. I think most people realize she was full of shit. She was obviously clueless regarding our history.

^This!