I'll also note that the Nazis likewise claimed hyper-rationality. It's much easier to get your minions to exterminate whole classes of people when they think it's the logical thing to do.
It was the worship of reason that led to these atrocities. Remember the "Goddess of Reason" that Robespierre wanted the French people to worship? That led directly to The Terror.
Ahhh, I get it. Let's just resolve to be very skeptical of any organization that claims, without proof, to be rational or to hold a higher truth. That'll keep us both from error.
Thanks for mentioning the French Revolution. That fountain of many miseries ... Marxism and Fascism at the least.