"Why should the childless subsidise any school? " Well, presumably because taxes aren't just for those things from which the taxpayer expects to receive direct benefit, and said childless taxpayer may well have need of the services of doctors, nurses, lawyers, accountants in the future, or may want to visit museums, which need curators, or read current research on history, which needs academics - all of these people that the childless may need in the future need to go to school.
I think people forget that many atheists started out religious and gradually became atheist, so it's not true that they don't understand the life of those who believe in a god, they just don't share that need.
I also think that we tend to see, in general, attacks on that which we hold dear far more quickly and clearly than on things that we either don't care about, or dislike. So I'm drawn to this thread because I'm an atheist - if I see a thread saying AIBU to think all Buddhists are tossers, I may not even really register it's there. So it may seem to believers that they're constantly under attack, but it's a question of perspective.
fwiw, I'm a happy atheist, just wishing that my children didn't have to "worship" something in school until they're old enough to make the damn decision for themselves. And I do get irked by the "the country has been Christian since time x" as there are lots of things that have been there for a long time - it doesn't make them immune to change. Women not having the vote would be one, and the country being Catholic, rather than Protestant...