It should also be noted that smart people are more likely to behave the way they are supposed to behave, so there’s the phenomenon that smart people are more likely to attend church even though they are less likely to believe in the religion, if attending church is deemed to be the proper behavior in their social group.The GSS offers a way to empirically test that assertion. The table below shows the average IQ** of four categories of people based on their perceptions of the divine; atheists, agnostics, uncertain believers, and firm believers. To get at the issue HS considers, only those who attend church at least "several times a year" are included:
The GSS suggests HS is incorrect. Instead, it looks like those who know they don't know but buy into Pascal's Wager are the smart cookies.
The sample sizes are sub-optimal for atheists or for agnostics--when you're in a combined group that only comprises 7% or so of the population, that's often the case--and only one-quarter of all atheists report attending religious services at least several times a year, so we're considering a minority among a minority, constituting one-half of one percent of the entire US population.
These caveats addressed, like politically contradictory liberal Republicans and conservative Democrats, church-attending atheists appear to be dullards. Those who go to church and pretend to worship a fictional deity are not principled types who are willing to stand up for what they (dis)believe in. The ability and willingness to back up one's conclusions with actions is likely in itself indicative of a high level of intelligence most of these people lack.
GSS variables used: ATTEND(3-8), GOD(1)(2)(3-5)(6), WORDSUM
Parenthetically, the answer(s) that lead to inclusion in each of the four groupings shown in the preceding table:
Atheist--"I don't believe in God"
Agnostic--"I don't know whether there is a God and I don't believe there is any way to find out"
Uncertain believer--"I don't believe in a personal God, but I do believe in a Higher Power of some kind", "I find myself believing in God some of the time, but not at others", and "While I have doubts, I feel that I do believe in God"
Firm believer--"I know God really exists and I have no doubts about it"
* It should be noted the GSS shows that it is not only among churchgoers but also the population at large that agnostics (average IQ of 105.2) and uncertain believers (100.0) are more intelligent than atheists (98.2) and firm believers (96.5) are. This doesn't strike me as surprising--cliched though it may sound, like theism, atheism requires one to hold beliefs about the supernatural that cannot be positively confirmed or disproved. Is it at least remotely possible that God exists but has intentionally ensured that no human will ever be able to prove as much? That is, might even the most advanced natural methods be incapable of detecting the supernatural? I'm unsure of how one argues that it is, with absolutely certainty, impossible.
** Converted from wordsum scores under the assumptions that the average IQ in the US is 98 and that one standard deviation on the vocabularly test is equivalent to 15 IQ points.