I have encountered a couple of instances recently where theists were particularly concerned with atheism being a motivation for charitable actions.
One is a challenge from the blog parabiodox for proof that "The Morality of Atheism is superior to that of Christianity."
The other came through private email, which contained the statement,
[I]sn't that a mark in favor of theism, since it encourages the religious to do good things, since they feel inspired by God to be good people?
As for Gates and Buffet, they are very generous men. But I don't think they give explicitly because they are atheist or agnostic. Since you seem to be preoccupied with this subject you might have some quote at the ready from Gates about how being an agnostic makes him a generous man.
These comments provide excellent examples of missing the point. The argument is trying to say that because atheism does not imply a moral view, that this is a mark against atheism.
Atheism and a Moral View
I have stated repeatedly that atheism does not imply a moral view. In this regard atheism is like heliocentrism (the view that the sun is at the gravitational center of the solar system). Heliocentrism also does not imply a moral view - it implies nothing about the difference between good and evil. However, we would not argue that it this is a fault with heliocentrism - that it is a reason to reject it. Similarly, atheism's lack of a moral view is not an objection to atheism. Both beliefs are equally compatible with the option that, if you want to study morality, you look someplace else.
We would certainly not argue that the propositions of mathematics or geology should be tossed out because they fail to provide any particular motivation for charity. This is not what mathematics and geology are about. Mathematics and geology effectively say, "If you want to study motivation for charity, you need to study some other subject. We do not cover that topic here."
Atheism is the same way. It is simply a belief that, "The proposition, 'At least one god exists' is (almost certainly) false." This does not tell us anything about what we should or should not do. The study of reasons for and against doing things looks elsewhere.
Holding Charity Hostage
Now, I want to look at the argument more closely. When we do, we see that the argument actually travels in a very small and tight circle. The argument states that belief in God is necessary for a motivation to behave charitably and that it is a fault with atheism that it does not motivate a person to act charitably. This is what makes theists 'better' than atheists - because they have a foundation for charity without which the motivation to give to charity would die.
However, while the argument asserts that belief in God promotes charity, the argument actually uses the value of charity to motivate belief in God. It takes the value of charity as a given - saying that it is a good thing that none of us would want to be without. Then, it holds it hostage, threatening dire harm to charity unless there is belief in God. Like a kidnapper who insists on the payment of a ransom or else the kidnapped child will die, the theist in this argument insists on a payment of 'belief in God' or 'charity' will die.
Unfortunately, for this hostage scenario to work, charity has to first have value - it has to be something that people want to protect. If somebody were to try to extort money from me by, say, threatening to smash some random rock into several pieces, they would scarcely get my attention. They have to choose something that I value. The hostage takers, in this case, have to assume that charity has value. Otherwise, threatening to destroy charity in the absence of belief in God is an empty threat.
Determining What God Values
Ultimately, it is not the case that humans love charity because of God. It's the case that humans love charity and, as a result, assign a love of charity to God. Humans created God and endowed God with the things that humans value - things that humans came to value without any belief in God.
Indeed, religious ethics all work this way. The reason why priests find the things that they value in God's will is because the priest assigned the things that he values to God. He then goes out among the people and says, "Behond, God himself values all of these things that we hold dear." Of course God values these thing - because the priest assigned the things that we hold dear to God.
Of course, the morality written into the Bible is not the morality of the priests living today (except, insofar as the priests pick and choose which biblical passages to obey and how to interpret what they read). The morality written into the Bible represents the values held by priests who have been dead for millenia. The reason the Bible says nothing particularly bad about slavery and held women in such low respect is because the priests at the time were slave owners who demanded that their women "love, honor, and obey".
The problem is that the people who wrote the Bible and who invented the morality written into it were far less than perfect. Many of the things they wrote, in ethics as in science, were siply wrong. As a result, to the degree that we follow their instructions, we would be repeating their mistakes - judging based on their ignorance - and doing things we should not be doing (behaving imorally) as a result.
It is not God who wanted these things, it was people in a position of political and social power who wanted them. And it is simply not the case that everything they wanted and that they claimed God wanted as well was something that they (or God) had a right to want.
If I were designing T-Shirts with catch phrases, this is one that I would include in my inventory.
Claiming that the Bible is the final word in morality is like claiming that Hippocrates is the final word in medicine.
It is not the case that everything that Hippocrates wrote about medicine was wrong. It was just primitive and ill informed. Still, he did pretty well for a person from that era. Today, we know much more. As a result, a patient is much better off going to a modern hospital than following the prescriptions of a doctor who insists that anything after Hippocrates that contradicts his teachings are rubbish.
It is also the case that those who wrote the Bible did not get everything wrong. They recognized the wrongness of murder, theft, and lying, even where they still condoned many acts that reasonable people today would recognize as murder and theft (particularly the murder of and theft from those who did not share their religion). However, they got a lot of things wrong, including a failure to mention that slavery and rape were moral crimes, a failure to promote democratic institutions and freedom of speech, and sanctioning the murder of those who belonged to different religions. We know better. As a result, people are better off following the prescriptions of modern moral thinkers than following the prescriptions of an ethicist who insists that civilization reached moral perfection 2000 years ago and everything we have learned since then is rubbish.
So, yes, it is the case that atheism does not imply any set of moral principles. This is because atheism says that morality comes from 'someplace else'. It's the same 'someplace else' that was used when humans invented God and attributed moral worth to him. Only, we have an additional 2000 years of knowledge under our belts - knowledge that rational people would use to correct the bigotries and prejudices that are 2000 years old.
So, one does not have to worry about the fate of charity if people started to doubt the existence of God. If it was not for an independent love of charity, the theist's threat of, "Obey my instructions or sweet charity will get one right between the eyes," would not have any power. Charity is one of the values that humans assign to God because humans value charity, and would continue to do so, even if they ended the practice of assigning its favorite values to a diety. Those values would still exist.