I liked that article because it reinforces what seems obvious to me, although there's a (slight) chance I could be mistaken : )
Thanks for posting the article. I like that people are trying to investigate sociological aspects of religiosity, and attempting to be scientific about it.
My semi-random 2¢ comments-
Meta-analysis is nice at bringing together disparate studies, so we get an overview. It can oversimplify, because different studies have different constraints, and may be incompatible with other studies. I think it's best to present with more information about why some of the studies showed religious people as more intelligent and others as less. It's either random variation, or the population examined, or the biases of the reviewer. I would like for the article to have been more detailed and give more context.
I noted this article, stating that more religious people are less intelligent, was illustrated with a pair of brown hands holding a rosary. Subconsciously, that comes off as feeling racially biased. Likely unintended, and there is much information out there that religion is in fact distributed differently among ethnic groups. But throw in the "intelligence" issue, and it adds an unwarranted flavor to the discussion that should focus, not on ethnicity, but rather on the topic at hand. The editors need to be more alert.
I tend to agree. A meta analysis doesn't necessarily rule out all bias, though that is purportedly the goal and hopefully the general result. It's important to remember that absolutes probably don't exist in nature.