The conclusion they came to was that there was no real difference between fundamentalists and everybody else. "The fundamentalist mentality is part of human nature." writes Stuart Sim, a cultural theorist at the University of Sunderland in the UK. "All of us are capable of exhibiting this kind of behaviour".
Attention has now turned away from individual psychology to focus on the power of the group. "We evolved to have close and intimate group contacts: we cooperate to compete, "says Atran. The psychology of fundamentalism is, literally, more than the sum of its parts; taken individually, fundamentalists are rather unremarkable. "The notion that you might be able to find something in a fundamentalist's brain scan is a non-starter," says John Brooke, a professor of science and religion at the University of Oxford.
My thought on this issue are probably best summed up by my rather incomprehensible essay on zealotry. To avoid the difficulty associated with making it through that post, I suspect that what we normally consider cultish zealotism is just an intersection between the high points on a couple of bell curves: one representing how easily people zone into to something, one representing how much an institution encourages such zoning, and the last being how uncommon chosen behaviours or interests are.
From a religious standpoint though, I think it is important to recognize that zealotry and fundamentalism, in whatever area most likely represent the easy road to escapism. Sure one can argue that biblical injunctions to extreme devotion are divinely mandated, but I don't believe imbalance and unsustainable actions designed to make or break us into relying on Jesus are necessarily the best way for long term progression. Continually laying down a gauntlet of fundamentalism, hoping that God will always be there to properly direct seems rather manic. Plus it seems to force an overly taxing solution on God when it would be much simpler for us just to move out of this rather selfish externalism.