A recent study discovered that belief in God among academics, by discipline, was ordered about like this:

(Most Atheistic)
Biology
Physics
Sociology
Psychology
Economics
Political Science
Chemistry
(Most Theistic)

"Does God exist?" is mainly a philosophical or religious question, an area in which "verbal" (non-numerical) reasoning is most important. However, if we look at the GRE scores (h/t Vox Day) of these disciplines, we find that percent of atheism doesn't neatly correlate with logical (non-quantitative) reasoning abilities. In fact, the correlation appears (except for Physics) to be somewhat inverse:

(Strongest Verbal Reasoning Skills)
Physics
Political Science
Economics
Biology
Chemistry
Sociology
Psychology
(Weakest Verbal Reasoning Skills)

Besides those shown, Philosophy, English, History and Religion majors thoroughly trounced Biologists, Physicists and Sociologists in non-mathematical reasoning. So it would seem the average atheistic biologist has poorer logical abilities than a theologian-in-training. (While I could easily accept the opposite outcome, I'm not surprised, given the rather poor reasoning behind some of (say) Richard Dawkins' arguments. He may be a respected biologist, but he seems to make a lot of really basic mistakes in his logical arguments.)

The GRE scores above would also seem to undermine our cultural belief that "scientists" are the smartest people in the population. True, scientists are sharper than the average non-academic, and many have truly stunning quantitative (mathematical) reasoning abilities -- but it seems that in terms non-mathematical reasoning skills, they're not even the smartest among academics.

Like philosopher Keith Burgess-Jackson, I don't think that intelligence really determines that much about whether a person is likely to believe in a religion or not. What I think is going on here is that materialists tend to turn to science as a kind of surrogate religion; I suspect intelligent religious people tend to be attracted to other disciplines (such as philosophy, theology, or medicine -- the last having a very high percentage of God-believers) or non-academic pursuits.

And indeed, the aforementioned study came to the same conclusion -- it wasn't so much that scientists' exposure to science turned them from believers to unbelievers, but more that they were unbelievers in the first place.

Our study data do not strongly support the idea that scientists simply drop their religious identities upon professional training, due to an inherent conflict between science and faith, or to institutional pressure to conform.... It appears that those from non-religious backgrounds disproportionately self-select into scientific professions.

This information goes a long way towards refuting the (ironically) poor reasoning and research skills* displayed in atheistic arguments like this one, citing studies which found that scientists, academics, Mensa members, and other self-selected "smart" populations tend to disbelieve in God. Scientists aren't necessarily the smartest people out there, and a belief is not necessarily true even if smart people do believe it.**

(** I'm sure the average Marxist was historically much smarter than the average non-Marxist. Likewise, during the late 19th and early 20th century, scientists tended to believe the cosmos had no beginning, whereas the average Baptist didn't.)

(* The cited article also shows a marked tendency towards cherry-picking: For example, a 1950 study which implied atheists were more likely to help the poor is cited, but decades of evidence showing atheists are less charitable are omitted. And I would be embarrassed if I were founding citing, seriously, a 1927 study which treated the showboats who paid to appear in "Who's Who in America" as a representative sample, or citing a study which could be summarized: "Found a negative correlation between the strength of religious values and research competence. How these were measured is unknown"! Almost no studies after 1975 -- they seem to think the heydey of reliable sociological research was the 1930s and 1940s!)