People aren’t very good at thinking in terms of probabilities and statistical tendencies. It’s part of how our minds work; we categorise things in lumps. It’s why people get desperately offended when studies come out which suggest that, say, women on the whole are less interested in engineering than men are, and why you see those dreadful articles which say “well, I’m a man, and I don’t like engineering, SO THERE MR SCIENTIST” or whatever. Mentally, we visualise “men” and “women” as two discrete lumps, one of which is “above” the other in the space marked “interest in engineering”.
In reality, of course, “men” and “women” are vast populations of individuals, scattered randomly around engineering-interest-space. While it may well be the case that there is a weighting, that there are more men towards the top of that space, that tells you nothing about the specific man or woman in front of you. Whoever you are, however interested you are in engineering, it is a statistical near-certainty that millions of women are more interested in it than you are.
It might be an obvious fact, but it bears regular repeating, because about at a rough estimate I’d say about three-quarters of all unnecessary offendedness springs from someone thinking that “Group X has a statistical difference from Group Y at Activity Z” means that “All members of Group X are better/worse than all members of Group Y at Activity Z”.
The reason I’m saying this is because the internet is currently interested in a meta-analysis, published in the journal Personality and Social Psychology Review, which finds that atheists have a higher IQ, on average, than the religious. They base this on a review of 63 studies, but, as the authors say, this news isn’t new. The evidence has been around for a while.
There are several reasons given, including a suggestion that the more intelligent you are, the more likely you are to need empirical and logical reasons to believe something; and, interestingly, that the things that religion does for people (helping them to delay gratification for greater future reward; providing an “anchor” in their life in hard times) intelligent people have less need for, because they use other methods. It’s an interesting study.
What it isn’t, however, is something for atheists to crow about. Because, you see, you don’t get to say “Woo hoo some people who don’t believe in the same thing I don’t believe in are on average more intelligent than a different group of people who are”. Or, rather, you do get to say that, but it’s not very much of an achievement. (Also, there’s a whole debate about IQ and its culturally biased weighting towards abstract reasoning, which is fascinating – see the Flynn effect – but too long to get into here.) There no doubt is a tendency for there to be more atheists towards the top of “intelligence space”. But it’s nowhere near strong enough for us to be able to make any inferences about the specific religious individual in front of us.
TL;DR: while you and I might be atheists, and atheists might be more intelligent (on average) than religious people, that doesn’t mean that you and I aren’t thick as four short planks. Just try to bear that in mind.