More Religion, More Economic Development?

Samuel P. Huntington cites data from Kenneth D. Wald's Religion and Politics in the United States. The data is expressed in a chart that looks like this:

Huntington, and Wald perhaps, are quick to point out that the US is the exception to this correlation by pointing out that the US places above 50 on the economic development index and, instead of being near 0% in religious importance, has 51% of its population thinking religion is important.

There are several flaws with this conclusion:

1. Huntington and Wald are confusing correlation with causation. Further studies, particularly by Barro et. al. , have shown that the correlation isn't that strong that it can be depicted as a straight line. The scatter plot is cloud-shaped...and yes, it does have a sloping indication. However, Barro has shown that economic development decreases with church attendance but increases with beliefs in heaven and hell. The US may not be so much an exception as just a blip on the data cloud.
2. Even if the correlation were strong, it would ignore historical influences to the US exception. Post-WWII, the US was the only industrialized nation that had significant and sufficient capacity. This probably influenced any economic development studies through the 1990's when this data was analyzed.
3. According to other researchers, the importance of religion was low for most of the US history...as low as 20% in the constitutional formulation era. If so, then that might explain some of the rapid ascent of America's influence on the world stage through the nineteenth century. It's only recently that religious affiliation has been above 50%.
4. A strict reading of this chart would conclude that religion increases as the economy declines or is suppressed. In other words, as our outlook gets bleak, we look to heavenly help. We cannot say that our looking to heavenly help causes the economy to stutter. (One person has pointed out that this chart proves the laments in Psalms and other bible passages correct: the wicked seem to prosper.) One might also conclude that the more atheistic countries should be steamrolling over the others. Perhaps Marx was right?
5. In Huntington's book, he espouses that everyone should adopt Anglo-Protestant values with agreement on the American Creed, described as liberty, equality, rule of law, individualism, private property, civil rights, etc. If he really wanted the US to remain economically strong, he would push for less religion according to this.