The old adage is: Never discuss religion or politics. Interlocutors can't remain amicable when these subjects are raised.
Personally, I suspect your average Joe's grasp of politics and religion is tenuous at best, yet they figure strongly in his/her ego-identity. People realize, consciously or unconsciously, that they have no grasp of these subjects; that they are completely out of their depth in any serious political or religious discussion, yet they've got their egos and social identities pegged to them.
When you live in a house of straw you don't want people poking at your dwelling...
Intellectuals, on the other hand, know exactly why they believe as they do, and their greatest worry is that one of their opinions might be in error. They expect their friends to challenge their views at every opportunity.
Intelligent people are insulted when others fail to assist them in testing their opinions by failing to attack them at every opportunity.
Religion and politics are the best subjects for discussion,in
my opinion.