The irrationality of a group belief doesn't split the group it reinforce group cohesion.
The sacrifice you make to go against the popular trend makes an member of the group more loyal,if the group performs it's function.
The irrationality of old Religions and irrationality of the extreme left who deny biology are a feature not a bug, they keep the group united against other.
Believing in irrational is a loyalty test.
PS. You would think that America will be free from old gods and irrational beliefs.
After all you don't have an inquisition in America to check your correctness of faith. If you disagree with the elders you just move west.
But what we notice is quite the contrary: an explosion of cults, and irrational beliefs.
To the old Religions some new were invented.
In the old world religion reinforced ethnic identity being Catholic in Iberia meant to be Spanish or Portuguese. Being Orthodox in Balkans meant to be Greek,serb or Bulgarian. The religious Identity reinforced solidarity between different polities.
In US it seems that religion reinforced the in-group solidarity
I think America worth studying to learn more about human nature. The freedom there allowed expression of some characteristics that were repressed by tradition in old world.
