Morality is a a set of values evolved over a period of time for a set of people in a set place and time.
To say moral values are something developed by a set of people is to admit god has nothing to do with it, in other words, god and religion are just human constructs. This is just dandy for us atheists.
There is nothing innate about it. If it was innate then it should be same all over.
All peoples from every corner of this globe do share some common core principles out of which comes morality. Love, compassion, justice, fairness etc., are seen as moral by all peoples, irrespective of where they are from, or what belief they are reared in, or what their present convictions are. There is a biological explanation for this common human trait. There is lot of literature out there if one is interested.
One might be temped to argue why then there are people doing bad things. That is a different question and the answer to it will not alter the validity of the above. Aggression is just as natural as love and compassion. What is valued as moral is naturally selected by what enhances the survival and reproduction. In the aggregate, love, compassion, cooperation are more conducive to human survival and reproduction than aggressiveness. This is why the former is seen as "moral" and the later not.
Majority of values have been codified in religions, and now those values are the basis of our constitution.
This only goes to show religion is a human invention to make people behave in a way the establishment wants. I agree. Religion is simply a tool in the hands of the establishment to enforce the kind of order that is most beneficial to them, and one of the ways they accomplish this is to cloak religion with moral sensibilities that will be attractive to the masses because of their innate moral sense. This is the reason majority of these values got codified in religions. It is pertinent to note that these values cloak the sinister aspects of religion, and to hoodwink the masses into willingly adopt religion as a whole, sinister aspects included.
The U.S. constitution is a document that is very specific about keeping religion out of government. The U.S. constitution serves as a wall of separation between religion and government.
If left to themselves with no values the whole human society will fall apart.
The opening assertion of the argument was that morality is a set of values evolved over time. This assertion presumes a slow process of building rules that finally enabled larger and stable human societies to form. This is a very reasonable argument, but needs a little deeper examination. What criteria were used to select some rules as part of the moral code and not others? Why would these rules help in the formation of larger and stable human societies?
I submit that for a rule to be accepted as moral it must be seen as fair and beneficial by the members of the society. This means the people must have an a priori notion of what is fair and just. Then, a rule may be accepted as moral in so far as it is in alignment with those notions. In other words, human beings were already equipped with a notion of what is moral, therefore morality is innate to human beings. In summary, to be a moral person is natural for human beings.
Another way of looking at this is to see it as a case of the anthropic principle in action. We see somethings as moral and others not because of our innate moral nature that makes us see them as moral. The reason love, compassion, etc., are considered moral is because those qualities matched our innate sense of what is good and moral, not because of some external immutable and inerrant entity said so. It is for the same reason greed, anger, etc., are not considered morally good qualities. So, by way of the anthropic principle we can say that what is considered moral is based on our innate sense of morality resulting from millions of years of biological evolution.
Cheers!