How we know that atheists are just as moral as religious people

I have been reading Peter Singer's Ethics in the Real World, a collection of 82 short articles and essays by the prominent ethics philosopher. One of them, entitled Godless Morality (also available on the web), looks at whether we need to be religious in order to be ethical. Now, you might think the answer obvious, but an awful lot of religious people apparently believe it to be true, arguing that it is God that gives us our sense of morality.

Unfortunately, a simple study using an online "moral sense test" gives the lie to that line of thinking. It seems that the responses from atheists to various hypothetical moral situations are almost identical to those of people who consider themselves religious. This suggests that our shared basic morality comes not from learned religious doctrine or directly from some God figure, but from our underlying humanity: we have an intuitive judgement of right and wrong, as a result of millions of years of evolution as social animals. No surprise to atheists perhaps, but a bit of a kick in the face for many religious people.

It's also interesting to consider the overwhelming responses to three of the situations in the test:

1. A runaway trolley is about to run over five people walking on the tracks. A railroad worker is standing next to a switch that can turn the trolley onto a side track, killing one person, but allowing the five to survive. Flipping the switch is ______.
2. You pass by a small child drowning in a shallow pond and you are the only one around. If you pick up the child, she will survive and your pants will be ruined. Picking up the child is _______.
3. Five people have just been rushed into a hospital in critical care, each requiring an organ to survive. There is not enough time to request organs from outside the hospital. There is, however, a healthy person in the hospital's waiting room. If the surgeon takes this person's organs, he will die but the five in critical care will survive. Taking the healthy person's organs is _______.

The three possible responses are "obligatory", "permissible" and "forbidden". A solid 90% of respondents answer "permissible" to No. 1, 97% say "obligatory" to No. 2, and 97% reply "forbidden" to No. 3. What is interesting is that there is such a consistency of opposite opinion between Nos. 1 and 3, both of which result in the saving of five people at the expense of one, albeit in different circumstances. Arguably, this shows more about human psychology - of atheists and theists alike - than about morality.