This argument reminds me of Dostoevsky’s position on religion. It’s not clear whether he actually believed in God (he did not as a young man) but later in life came to the conclusion that religious belief was necessary for order because of people’s capacity to rationalize just about any sort of behavior on their own: ‘without God everything is permissible’. It’s a famous line.
There are many atheists I have encountered that basically said the same thing, and that while they do not believe themselves, they do shudder to think what a world without some kind of belief in a higher being would be like.
I can tell you, it wouldn’t be pretty. Yes, John Lennon, I imagined a world with no religion, and it’s horrifying.
Of course indulgences prove that even with God everything CAN BE permissible for a small cash donation.