Where this argument specifically addresses charges posted by cerenziam, that Morality and Charity can only come from a belief in god and Christianity, it is a response to Christian CHAUVINISM in general. ( See original posts here: http://www.bigthink.com/faith-beliefs/9116 )
The argument that Morality is based upon belief in god; that Morality is born of the Christian faith; that NO-GOD = Nihilism: these are falsehoods learned in Christian schools. Morality is codified within the Human Song, the genetic and cultural programming that makes us Human. Some of it is instinct and some we learn at our mother's knee.
The argument that belief in god is the wellspring of Morality actually boils down to Fear-of-god or Fear-of-damnation = Morality, an extension of our approach to criminal justice. But when we look back into the wellspring of history we see Morality has always been coded.
Long before the times of Yahweh Jesus or Mohammad, we find law which codifies human Morality. The oldest writings so far discovered and deciphered contain the moral code that later was appropriated by Yahweh. (The story of Noah is older than the Hebrew people and is in fact repeated by mythologies around the world, including North American Coyote mythology.)
In fact Charity as a part of Morality is so old that it predates our species. The latest in Neanderthal anthropology has revealed that this species did not walk hunched over as previously assumed. The incorrect assumptions were based upon the examination of found skeletons, which were found because they were ritually buried.
The skeletons were bent over from old age, calcium loss, and arthritis. These people had survived because their culture loved them and cared for them so that they could survive to old age. The bodies are often found with the remains of flowers and trinkets indicating, not only love, but a belief in the afterlife.
It is now understood that the Neanderthals did not die off as previously assumed, but were killed off in warfare with our species, Cro-Magnon, as our forefathers spread across the planet. In fact this could be seen as the Original Sin: that a more violent and competitive (and perhaps less moral) human animal arose. And where did this genetic change come from? All our mythology, including the Bible, informs us that 'the sons of god' are to blame. Coyote mythology informs us that Coyote is our father (or mother), and that this is the source for all that ails human morality, but I digress. (It's our mother's fault.)
So, where it is admitted that Christianity has influenced our Morality, to argue that Christianity is the SOURCE of Morality or Charity, is Christian chauvinism, and false. For example the Pentateuch codifies specific ancient acts of charity which are NOT followed by todays Christian culture.
Morality is codified within the Human Song, the genetic and cultural programming that makes us Human. We have seen that those who feel rejected by their culture often turn to immoral behavior such as crime. What is interesting is that those in positions of power also seem to abandon moral code, as if the holding of power necessitated immoral behavior as per Machiavelli.
So where the Catholic Church for centuries exhibited immoral behavior because of its power, Charity as acts-of-cultural-change did not appear until Christian rebels -Protestants- threw off the mantle of the ancient Church. And where Protestantism rose to power, such as the Bush administration, again we see that Morality and Charity is cast aside as unbecoming to power.
And where Christianity raises up a new Moral Hero, as in Senator Obama, he is castigated for adhering to a Christian minister that radicalizes the issue of moral standards and criticizes the moral behavior of white American culture. Again, I digress.
The idea that Human Morality is codified within humanity's heart is NOT a purely secular idea. In fact the old prophets of the Bible said the same thing: that god admits that a written code based upon the fear-of-god DOES NOT WORK, and that god would 'write his laws upon the hearts of men and women.' Morality comes from within Humanity and not from god; even the Bible tells me so.
Now lastly, this idea that NO-GOD = Nihilism. The common definition of nihilism is 'the rejection of all religious and moral principles, in the belief that life is meaningless.' Now where this applies to Islamist terrorists who reject the moral code of their own faith in order to justify murder to gain their place in the next world, this does NOT INDICATE a lack of belief in god. The Islamists are religious fundamentalists, and as our own Evangelicals, they pine for the end-of-this-world (i.e: the belief that life is worthless).
In fact Nietzsche's definition is different and he saw belief in god as leading to nihilism. And this is where Christians pick and choose among the multiple meanings that best suits their accusations against atheists. Most words have multiple meanings and it is dishonest for Christians to ignore Nietzsche's while suggesting that what he meant was NO-GOD = Nihilism.
NO-GOD = no-Platonist-ideas-of-the-IDEAL. Where Plato argued that we could never have a proper 'chair' in this world, because the ideal of 'chair' could never be realized, so as with Morality. The Ideal-of-Morality was god; if you remove god, then morality supposedly ceases to exist.
In the same way, if we kill Plato, then NO OBJECTIVE TRUTHS could exist. This does not mean that Truth ceases, but that all truths are subjective to human experience culture and instincts (genetic). Nietzsche did not say that if we kill god and Plato that humanity would abandon Morality; what he said was that those that cling to Plato would DESPAIR of this world, even as we see in Islamist terrorism. Nietzsche despaired that humanity would fall because we are addicted to god-belief and that we would never be able to rise to the next level of awareness.
Proof that Objective Truths DO NOT exist and that the Subjective is more REAL is in the Placebo experiment. A patient receives pain relief from a saline injection believing that he was receiving pain medication. It does not matter so much what is REAL, as what we believe to be real.
So the Christian argument boils down to: we don't need a REAL GOD, we just need to BELIEVE in a god to be moral human beings. And that is what cerenziam was arguing as a Christian wanna-be, and that is proved false.