This is contrasted with rates among the general public who, in this country, profess belief with almost opposite regularity.
I have no theory about the cause. I just I’d point out some factors that may contribute:
- Maybe it's true. Maybe smart people really are less likely to believe. Perhaps (I don’t buy it, but perhaps) this is an example of foolish things putting the wise to shame.
- Christian higher education devalues and in many cases demonizes science, redirecting bright Christians into seminary. Among Christians there is a brain drain from science to theology and ministry.
- Academia is not the only employer of Ph.D. scientists, or even of exceptionally gifted Ph.D. scientists. Industry takes its share. Perhaps the percentages are quite different there, indicating a bias where talented believing scientists are more comfortable taking that path. (I have no data—just speculating.)
- Perhaps extremely talented people are simply more secure and confident. Thus while your average Joe might, from peer pressure, be reluctant to profess his atheism, you average scientist with his Ph.D. sized ego is not. In other words, the percentage of sincere God believers may be way, way less than polls indicated, reducing the disparity between scientists and non-scientists. (In this model, the 7% of NAS believers must be stalwart paragons of sincerity. A doff O’ the cap to ‘em.)