“Religious communities actually protect their members from religion in one sense – they develop an unspoken consensus on which parts of their religion members can legitimately ignore. New converts sometimes try to actually do what their religion tells them to do.
The history of religions sometimes resembles the history of viruses. Judaism and Islam were both highly virulent when they first broke out, driving the first generations of their people to conquer (Islam) or just slaughter (Judaism) everyone around them for the sin of not being them. They both grew more sedate over time. (Christianity was pacifist at the start, as it arose in a conquered people. When the Romans adopted it, it didn’t make them any more militaristic than they already were.)
The mechanism isn’t the same as for diseases, which can’t be too virulent or they kill their hosts. Religions don’t generally kill their hosts. I suspect that, over time, individual selection favors those who are less zealous. The point is that a culture develops antibodies for the particular religions it co-exists with – attitudes and practices that make them less virulent.
I have a theory that “radical Islam” is not native Islam, but Westernized Islam. Over half of 75 Muslim terrorists studied by Bergen & Pandey 2005 in the New York Times had gone to a Western college. (Only 9% had attended madrassas.) A very small percentage of all Muslims have received a Western college education. When someone lives all their life in a Muslim country, they’re not likely to be hit with the urge to travel abroad and blow something up. But when someone from an Islamic nation goes to Europe for college, and comes back with Enlightenment ideas about reason and seeking logical closure over beliefs, and applies them to the Koran, then you have troubles. They have lost their cultural immunity.”