Major proble with their conclusion and a classic example of "correlation not being causation":
how do the researchers know that their fundamentalism was due to the brain injury and that they did not, in fact, already have such fundamentalist beliefs prior to the trauma? They only have access to intelligence from before they got the injuries, not a pre-injury fundamentalism survey.
I'm also concerned that about 33% of the test group (about 40 out of 119) and 41% of the control group (12 out of 30) declined to mention their religion, meaning their control group is statistically insignificant (18 ) . Here is a link to the actual study for further dissection BTW: