From Phil Zuckerman’s Living the Secular Life (New York: Penguin, 2014), p. 46:
Drawing on numerous international surveys that reveal what percentage of the population in various countries believes in God, has faith in God, prays to God, and so on, we are able to get a fairly good, reasonably accurate, and widely agreed-upon list of the most and least God-worshipping nations in the world. The most faithful nations on earth—those highest in theism—include Nigeria, Uganda, the Philippines, Pakistan, Morocco, Egypt, Zimbabwe, Bangladesh, El Salvador, Colombia, Senegal, Malawi, Indonesia, Brazil, Peru, Jordan, Algeria, Ghana, Venezuela, Mexico, and Sierra Leone. And as for the least faithful, most secular nations on earth—those with the highest rates of atheism, agnosticism, or theological indifference—we can include Sweden, Denmark, the Czech Republic, Japan, Canada, Norway, Finland, China, New Zealand, South Korea, Estonia, France, Vietnam, Russia, Bulgaria, the Netherlands, Slovenia, Germany, Hungary, Great Britain, Australia, and Belgium.
Okay, so which set of countries is faring the best, on average? According to the claims of many Americans, it should be the most God-loving nations. But such is not the case. Far from it. Rather, it is those countries with the lowest rates of God belief that tend to be the “healthiest” in terms of prosperity, equality, freedom, democracy, women’s rights, human rights, educational attainment, crime rates, life expectancy, and so forth (though not all, to be sure, such as Vietnam or China), and it is those nations with the highest rates of God belief that tend to be relatively unsuccessful in terms of any standard sociological measurements of societal health—from having high infant mortality rates to high poverty rates, from entrenched inequality to a stubborn degree of corruption, from lack of clean water to absence of democracy.