Andrew Brown has a longish post on IQ and religiosity, among other things. It’s worth a look, but I’m reproducing a bit of it here for the Wesley quote.
The tricky relation between religion and IQ
… But could something similar be true of religion? In particular, could dogmatic and fundamentalist religion be more useful to the poor and wretched? Could it lift them to the stage where they could experiment with doubt, with nuance, with novelistic thinking? The history of the early Methodists suggests exactly this. Remember John Wesley’s reflection on his own success:
The Methodists in every place grow diligent and frugal; consequently they increase in goods. Hence they proportionately increase in pride, in anger, in the desire of the flesh, the desire of the eyes, and the pride of life. So, although the form of religion remains, the spirit is swiftly vanishing away.