The question isn't about a mild mannered-individual growing up in a culture shaped by religion. Can an atheist society thrive for generations, has it ever?
If America was suddenly sprayed with a chemical that removed all belief in God, and made everyone 100% purely free of any concept of God and a soul and an after life, and removed all residue and traces of any connection with that past, I don't think that the result would be positive.
I really don’t know if there have been any purely atheist societies, or pure any beliefs. I doubt there ever has, knowing human nature.
I imagine that’s why God made so many different types of people over the ages.