That's well said, but remember that this is just a thought experiment. I'm trying to imagine an ideal atheistic society, which I take to be one founded on an existential perspective. You're talking about enforcing atheism, but I'm assuming the society is effectively atheistic, on whatever grounds those might be.

Certainly, in practice, existentialism has been marginalized because the masses prefer easier solutions. That's the case with all intellectual countercultures: they end up serving an underground elite. But what if more people became convinced that liberalism and collectivism are dead ends, and they became more philosophical about their effective atheism? How would an existentially authentic and atheistic society work in theory? That's what I'm starting to imagine here.

It's a thought experiment, and you might be right that this society wouldn't work at all. But I don't think it's so obvious either way, even if at present it would certainly be unworkable in practice.