http://psychcentral.com/news/2011/09/21/cognitive-style-tends-to-predict-religious-conviction/29646.html
Participants who gave intuitive answers to all three problems [that required reflective thinking rather than intuitive] were one and a half times as likely to report they were convinced of God’s existence as those who answered all of the questions correctly.
Importantly, researchers discovered the association between thinking styles and religious beliefs were not tied to the participants’ thinking ability or IQ.
participants who wrote about a successful intuitive experience were more likely to report they were convinced of God’s existence than those who wrote about a successful reflective experience.
I think this is the source but I can't be sure:
http://www.apa.org/pubs/journals/releases/xge-ofp-shenhav.pdf
http://lesswrong.com/lw/7o4/atheism_autism_spectrum/4vbc
I thought there is a negative correlation between Religiosity and IQ?
There can still be. It's possible for there to be a correlation between thinking style and religiosity and a different correlation between IQ and religiosity, even if thinking style and IQ are uncorrelated.
Looks like this study was trying to focus on the former while filtering out the latter.