Lily, I do accept that people are hurt, or say they are offended, when certain beliefs they hold are mocked. I also argue that that's something they have to live with in a free society. They have the same freedom to mock my beliefs as I have to mock theirs. Feeling hurt/offended by what someone else says is part of the price of freedom.
The "You can't say that, I'm hurt/offended hoo-ha" is just a shutting up device. If people give in to it, they are cow-towing to bullying.
There was no preaching or ranting in the OP. Just amazement and, yes, ridicule. But mice's explanation subdued that and was accepted. She didn't argue that people shouldn't mock; she gave them a reason not to.
I still think the whole indulgences malarky is bonkers, but if some people gain something from believing in it, that's fine by me. But I'm still allowed to believe it's bonkers AND TO SAY SO.