Religion and Economic Growth

Robert Barro contends that the extent of religious beliefs and economic growth are inversely related. The United States is an outlier in that as a whole the U.S. population is highly religious (evangelical at that) and yet we have a very vibrant economy. I think that Don Boudreaux, referencing Joel Mokyr's book The Gifts of Athena, might have an explanation that would account for differences in economic growth among countries that tend to be more religious, based on belief systems that positively or negatively influence economic growth.

Addendum: Let me clarify my point. Barro finds a negative correlation between the extent of religious belief and a nation's economic growth. My point is that religion itself is too ill-defined and paints with too broad a brush to be a valid predictor; there are wealthy countries with a large percentage of their populations devoutly religious and poor countries that aren't. My point simply is that maybe by differentiating between the mystical beliefs of various religions you obtain a better predictor of a country's economic growth.