It's not the content of the belief, its the response to the belief that matters. That's what I witnessed in my two years living among a group of high-end fundamentalists.
Let's say I believe the world will end through global warming. My neighbor believes the world will end when Jesus comes to slay non-believers and take believers to heaven. My response to my belief is to buy guns to fend off the hordes of beach dwellers I expect to swarm my upland property. My neighbor's response to her belief is to stock up canned goods and plan to share them with all comers in the last days.
Which one of us is more spiritually advanced?
Without getting into the distinctions between the ethical line, the spiritual line, and the congnitive line of development, I'll just say for myself, I'm glad she's my neighbor! (For fans of Ken Wilber, the four possible definitions of "spiritual" are on page 101 of "Integral Spirituality")
And yes, mythic beliefs are often correlated with ethnocentric behavior. But not always. And I believe that distinction is key to relieving some of our prejudices against each other and thus making room for new responses. It can often be easier to change a response than change a belief.
Change your response, change your life.
Photo from Southern Foodways Alliance.