Michael Fitzgerald sorts through a number of studies on the economic effects of religion:

Among the most provocative findings have come from Robert Barro, a renowned economist at Harvard, and his wife, Rachel McCleary, a researcher at Harvard’s Taubman Center. [...] The two collected data from 59 countries where a majority of the population followed one of the four major religions, Christianity, Islam, Hinduism, or Buddhism. They ran this data - which covered slices of years from 1981 to 2000, measuring things like levels of belief in God, afterlife beliefs, and worship attendance - through statistical models. Their results show a strong correlation between economic growth and certain shifts in beliefs, though only in developing countries.

Most strikingly, if belief in hell jumps up sharply while actual church attendance stays flat, it correlates with economic growth. Belief in heaven also has a similar effect, though less pronounced. Mere belief in God has no effect one way or the other. Meanwhile, if church attendance actually rises, it slows growth in developing economies.