Nature and origin of morality

Introduction
Upon reading Hitchen’s controversial book “God is not great” and inspecting his extrapolated evidences of how as he mentions numerous times that “religion poisons everything”, it seems more appropriate to have named the book as Religion is not great. Besides, this isn’t a book review, rather a take on what on which candle this book lit up whilst I read it’s contents. I have to start this with a disclaimer: this is merely an exploration of my incomplete thinking, not a thoroughly researched exposition.
As Hitchen’s goes on chapter wise on the various actions or effects believers of various faiths have made in human history, it becomes quite evident through the book how he categorically incorporates and touches the detailed aspects of human history, philosophy, science to make his case of how people of the modern age must resort to science and practical reasoning rather than turning to blind faith. How in ancient times, to support theories of then considered anomalies, the masses would turn to a belief in the powers that be and now that mankind has made tremendous advances in science, we must discard belief in a singular or multiple powers that decide on the laws of the universe. This read is ideal for an atheist’s validation in their stand. The concept of nature and origin of morality and their take from an atheistic and their counterparts perspective seemed quite intriguing.
The Argument
The claim of a believer is that morality can only be derived from god. From the atheists there is a ruling out of god as the possible reason. It can be seen how either of the views seem to be arrogant and claim ownership, since morality is a desirable virtue. By implication, those who are non believers would lack morality or vice versa. Such accusations, judging one’s moral conduct have been made and in my opinion are ungracious and unhelpful. Let’s consider the possibility that the proposition is true on one side. Where would that leave everyone else? Do they lack morals altogether? A quick look at society would suggest not.
Can we rule god out of morality? If the answer is yes then there must be another source of morality… the quickest alternative that comes to mind is evolution. The main goal in early ages of evolution was to survive, so for a society to be sustainable the necessary patterns of behavior would dictate that certain morals were followed. This methodology of how morals developed is not without flaws. Only through trial and error would the generations learn and adapt to such intricacies. We cannot accurately trace at what stage in human evolution the notion of morality first cropped up, we can only look at the way we are now.
The argument that morality starts with God, as something inbuilt into humanity, certainly helps our understanding of why so many aspects of morality would appear to be common throughout humanity. The case is not watertight, but as yet I do not seen a line of reasoning that necessitates the ruling God out of discussions on morality. At best, there can be doubts cast on this, for the usual reason of the never-answered question of the existence of God. Though as I have said before, as foundational as this question is, it’s not a helpful starting point; no more than trying to deflect any attempts at math before you have adequately defined what a number is.
The Conclusion
It is perfectly possible to develop a consistent morality yourself, without reference to God. However, morality with reference to God is also consistent. So to rule that morality is necessarily atheistic is premature. The pitfalls come when you try and codify morality. An analogy with respect to the constitutions of two nations to validate; In Britain, the constitution is unwritten; it is a matter more of collective understanding and a knowledge of history and tradition. In the US, it was codified. Now in Britain, if a political development is unconstitutional then it can be seen to be so simply through common sense(though I would prefer to use intuition). But in the US, the written nature has caused no ends of trouble, to the extent that people have the job of interpreting the written constitution. This has shown that when you have something codified, that it is open to misinterpretation and willful misunderstanding to suit a political motivation.
Moral behaviour is the human norm. It is something which is inbuilt in us, and which we are designed to do. Think of it a little like civil law, it does not tell people how to live. It tells us what the exceptions are which are not acceptable in society. So morality is best defined by negation, while all else is moral. Of course, I acknowledge that is merely my own view which may well be wrong, and would welcome alternative views or suggested further reading.