Jehovah's Witnesses have the least amount of college graduates and Pentecostals make the least amount of money.
Of course, when it comes to our belief systems, money and education are often of little importance. But we would be naive to think that there are no correlations between religious beliefs and education (and earning potential), just as we would be naive to believe that religious affiliations (and their communities) do not play a part in our employment opportunities (or lack thereof).
As David Leonhardt writes in the New York Times:
The relationship between education and income is so strong that you can almost draw a line through the points on this graph. Social science rarely produces results this clean.
He also warns of making too much of the religious aspect, since there are so many factors at work here:
Some of the income differences probably stem from culture. Some faiths place great importance on formal education. But the differences are also self-reinforcing. People who make more money can send their children to better schools, exacerbating the many advantages they have over poorer children. Round and round, the cycle goes. It won’t solve itself.