Before we get to the problem, though, read Singer's lede and his conclusion:
Imagine you come across a small child who has fallen into a pond and is in danger of drowning. You know that you can easily and safely rescue him, but you are wearing an expensive pair of shoes that will be ruined if you do. It would be wrong – monstrous, in fact – to walk on past the pond, leaving the child to drown, because you don’t want to have to buy a new pair of shoes. You can’t compare a child’s life with a pair of shoes!Do you see anything wrong with what Singer's arguing here? Here's a hint, Singer is an atheist.
Yet while we all say that it would be wrong to walk past the child there are other children whose lives we could save just as easily – and yet we don’t. UNICEF, the United Nations Children’s Fund, estimates that nearly 9 million children under 5 die each year from causes related to poverty. That’s 24,000 a day – a football stadium full of young children, dying every day (along with thousands of older children and adults who die from poverty every day as well). Some die because they don’t have enough to eat or clean water to drink. More die from measles, malaria, diarrhea and pneumonia – diseases that don’t exist in developed nations, or if they do, are easily cured and rarely fatal....
As people with more than enough, we have a moral obligation to help those who, through no fault of their own, are living in extreme poverty. It’s not hard to do.
On what conceivable grounds does Singer base his assertion that it would be "monstrous" to ignore the drowning child? On what grounds does he insist that we have a moral obligation to help those living in poverty?
What Singer and other atheists often do is piggyback on the Christian belief that a duty is imposed upon us by God to help the poor. He appeals to that sense of duty, tries to reinforce it and get us to live up to it, but at the same time he rejects the existence of the only being which can be a source of the duty - God.
For thinkers like Singer, allowing the child to drown offends his own personal value system (which is a little odd inasmuch as the man is famous for advocating infanticide), but his value system is an arbitrary set of preferences that apply to no one else unless they, too, choose to have the same preferences. When he says that it's monstrous to allow the child to drown all he's saying is that he doesn't like such decisions and he wishes people wouldn't make them. What he can't say is that the decision is objectively wrong.
When he speaks of a moral obligation we all have to help the poor he's talking nonsense - rather like saying we all have a moral obligation to like blue more than green. If moral values are merely matters of personal taste how could one man's preference possibly be obligatory for another man?
Atheists are somewhat like con-artists. They talk about objective moral values and duties and hope that no one will ever ask them to explain how there can be such things in a world in which there is no transcendent moral authority. Then, having hung these values in mid-air, so to speak, they turn around and chide Christians for believing that moral values are rooted in the Creator of the cosmos.
A famous example of the irrationality of this is the story of atheist philosopher Bertrand Russell who had been expounding his view that there are no objectively binding moral values. Then, mere minutes later, he was fiercely denouncing to his listeners a man he described as a "scoundrel".
It's sheer nonsense to claim that in a world without God anything at all could be morally "monstrous" or that we have an obligation to help people we don't even know. It's disingenuous for a non-theist to employ moral language that only a theist can rationally use. Even so, despite the irrationality of it all, atheists are fond of cloaking themselves in the mantle of reason while lecturing the rest of us on our moral obligations. We shouldn't let them get away with it.