On second thought, the persecution of Christianity in our public institutions is the real issue here. If the courts could respect religious expression in public schools to a reasonable degree, I think alot of tension between the two sides would be difused.
I'm pretty sure that religious expression is best left in the hands of religious organizations, not public schools. If religious expression were to be allowed in public schools, what sort of limits might be imposed? For example, ought muslims to be allowed to engage in muslim prayers in special prayer rooms paid for by taxpayers? Issues such as this make me think that it's for the best if public schools stick to non-religious topics.
This is not to say, though, that all mention of 'God' is to be expunged from school discourse. That would be absurd and a mis-construal of history.