Extreme religious beliefs are a perfect example of tribalism: the mental processes of people who don't actually decide what to believe, they just parrot whatever is most convenient for them based on their social circle
Discussion
Extremism is a whole another coversion. That mindset doesn't see any other option or way of being.
But if you did your thinking, and came to conclusion that our world is created...Did iceage happen? Are woolly mammoths real?
Those people usually believe in ice ages and woolly mammoths, just with different timing