There is exactly one example of officially atheistic country in the history. And it's not the USSR which was officially secular with freedom of religion.
Try to guess that country?
>Compare some US evangelicals' advocacy for sponsored prayer in state schools to French secularists' banishment of religious attire in state schools.
That is a good decision.
>It is not unreasonable to conclude these fall fairly close to each other on the modernity continuum while being poles apart on the faith continuum.
No they're not. There should be no religion in public schools, and that includes conspicuous and demeaning religious symbols.
Now, if atheists would demand to have equal time at any sermon or church service then it would be the same.