I guess one should really define first what insanity is. Maybe it really is just an alternative version of sanity. After all, if the majority do something which I regard as insane, then maybe I'm the one who's insane.
So let's say insanity is an affliction possessed by those who do not appear to conform to norms that I and those like me agree are correct. In that case, believers of religious doctrine are indeed insane. Why would anyone turn logic on its head in order to comply with something written in an alien culture thousands of years ago by people who hadn't the first clue why things were the way they were, and so invented reasons that made a kind of sense if one had no better alternatives - producing stories that were so outlandish that people thought they must be correct, on the basis that no sane person could possibly have imagined them whilst temporarily delusional as a result of eating the wrong mushrooms. (Pauses to take a breath...)
Surely to cling to ideas such as these which are so very far past their sell by date is a form of self delusion, by people who would prefer to believe comforting fiction than face uncomfortable fact. Crazy!
Or is it just me that's crazy? And does it matter? Ho hum....