:hmm:
Not sure I follow exactly.
Their claim to moral superiority - if not stated outright by every priest, bishop, and pope out there - is implicit in their dogma, and presumption that they can define sin, absolve sin through confession, grant access to heaven, etc. based on their (allegedly) divinely inspired church.
they certainly don't behave according to their own moral code, or often even how Jesus preached they should live: declaring Crusades, murdering other popes and religious rivals, selling indulgences, unleashing the Counter-Reformation/Inquisition when their authority was threatened, hoarding gold and money
see also e.g.:
And I don't think any progressives want to define morality. Now that's a stretch. At least I've never read anything about it. I'm okay with a criminal code based on respect for other's property & civil rights, and some basic instruction on why laws are needed (because the alternative is the jungle; anarchy). it's not about dictating anything, or being a prick about it, just basic common sense and decency.