The study itself makes no assertion of why
, but seeks only to demonstrate the correlation between cognitive function and what people are willing to accept with regard to beliefs.
Pentecostals, for instance, are among the more dogmatic of religious adherents and I don't think it would be a stretch or generalization to imagine that the vast and overwhelming majority of this denomination are conservative republicans.
Pentecostals, however, also subscribe to the most fantastic of beliefs -things that are completely without intellectual merit or expectation of being true
by those who are among the population who have higher cognitive function. Things like snake-handling, speaking in tongues (glossolalia), young-earth creationism, etc.
The prediction of the study is that this group would have a lower IQ (lower cognitive function) than more liberal groups. I actually didn't look at the table in the study before
choosing Pentecostal as an example, but it turned out that the prediction holds. Pentecostals scored an average of 101.89 as an IQ whereas atheists scored an average of 111.08.
Interestingly enough, and for those that might think so, I'm not asserting atheists are "smartest" nor is Nyborg. Indeed, the data are clear on this: The Episcopal/Angelican group scored the highest IQ at 113.43 with the Jewish denomination a close second at 112.43. Atheists actually placed 3rd and Agnostics 4th with an average IQ of 109.13.
When comparing religious denominations, Nyborg rated (by using the ratings of previous authors/studies) denominations as either liberal or dogmatic, defining both thus:
a. Liberal: fairly open, critical, less committed, metaphorical, cultural heritage-type persuasion.
b. Dogmatic: more committed, personal relationship with Jesus, emphasis on sinfulness, explicit rules for behavior and need for atonement.