Popular religious belief is caused by dysfunctional social conditions. This is the conclusion of the latest sociological research (pdf) conducted by Gregory Paul. Far from religion benefiting societies, as the "moral-creator socioeconomic hypothesis" would have it, popular religion is a psychological mechanism for coping with high levels of stress and anxiety – or so he suggests.

I've long been interested in Paul's work because it addresses a whole bunch of fascinating questions – why are Americans so religious when the rest of the developed world is increasingly secular? Is religious belief beneficial to societies? does religion make people behave better?

Many believers assume, without question, that it does – even that there can be no morality without religion. They cite George Washington who believed that national morality could not prevail without religions principles, or Dostoevsky's famous claim (actually words of his fictional character Ivan Karamazov) that "without God all things are permitted". Then there are Americans defending their country's peculiarly high levels of popular religious belief and claiming that faith-based charity is better than universal government provision.

Atheists, naturalists and humanists fight back claiming that it's perfectly possible to be moral without God. Evolutionary psychology reveals the common morality of our species, and the universal values of fairness, kindness, and reciprocity. But who is right? As a scientist I want evidence. What if – against all my own beliefs – it turns out that religious people really do behave better than atheists, and that religious societies are better in important respects than non-religious ones, then I would have cause to rethink some of my ideas.

This is where Gregory Paul and his research come in. I have often quoted his earlier, 2005, research which showed strong positive correlations between nations' religious belief and levels of murder, teenage pregnancy, drug abuse and other indicators of dysfunction. It seemed to show, at the very least, that being religious does not necessarily make for a better society. The real problem was that he was able to show only correlations, and the publicity for his new research seemed to imply causation. If so this would have important implications indeed.

In this latest research Paul measures "popular religiosity" for developed nations, and then compares it against the "successful societies scale" (SSS) which includes such things such as homicides, the proportion of people incarcerated, infant mortality, sexually transmitted diseases, teenage births and abortions, corruption, income inequality, and many others. In other words it is a way of summing up a society's health. The outlier again and again is the US with a stunning catalogue of failures. On almost every measure the US comes out worse than any other 1st world developed nation, and it is also the most religious.

For this reason Paul carries out his analysis both with and without the US included, but either way the same correlations turn up. The 1st world nations with the highest levels of belief in God, and the greatest religious observance are also the ones with all the signs of societal dysfunction. These correlations are truly stunning. They are not "barely significant" or marginal in any way. Many, such as those between popular religiosity and teenage abortions and STDs have correlation coefficients over 0.9 and the overall correlation with the SSS is 0.7 with the US included and 0.5 without. These are powerful relationships. But why?

The critical step from correlation to cause is not easy. Paul analyses all sorts of possibilities. Immigration and diversity do not explain the relationships, nor do a country's frontier past, nor its violent media, and so he is led to his conclusions: "Because highly secular democracies are significantly and regularly outperforming the more theistic ones, the moral-creator socioeconomic hypothesis is rejected in favour of the secular-democratic socioeconomic hypothesis"; "religious prosociality and charity are less effective at improving societal conditions than are secular government programmes".

He draws implications for human evolution too. Contrary to Dan Dennett, Pascal Boyer and others, he argues that religion is not a deep-seated or inherited tendency. It is a crutch to which people turn when they are under extreme stress, "a natural invention of human minds in response to a defective habitat". Americans, he says, suffer appalling stress and anxiety due to the lack of universal health care, the competitive economic environment, and huge income inequalities, and under these conditions belief in a supernatural creator and reliance on religious observance provides relief. By contrast, the middle class majorities of western Europe, Canada, Australia, New Zealand and Japan have secure enough lives not to seek help from a supernatural creator.

These are powerful conclusions indeed, and if they are right the US in particular needs to take note. But are they? I still retain some caution. I keep reminding myself of the obvious point that in science it is all too easy to apply a more critical eye to research whose conclusions you disagree with. In this case the wiggly route from correlation to cause includes many questionable steps, and clearly a lot more research is needed. I was also dismayed by what might seem trivial – the appalling number of typos and other mistakes in the only version of the paper I could find – the one that is linked from the press release and several other places. There are missing words, added words, "their"s for "there"s and other errors that sometimes made it hard to follow. If the text was so poorly checked, I wondered, what about the data? Should I apply my critical concerns to those stunningly high correlations too?

I guess we'll find out, for this is a hot topic and a thriving research area. For now we need not necessarily agree with Paul that "it is probably not possible for a socially healthy nation to be highly religious" but he has certainly shown that the healthiest nations are also the least religious.