[SubSailor]

The issue is the appropriateness of the school acknowledging the existence of a God, and once doing that acknowledging a God who can be called upon through a generic statement to bless America.

You didn't answer this question earlier, so I'll post it again: How could saying/displaying "God bless America" be misconstrued by any reasonable individual as Congress making a law respecting an establishment of religion? What law is being enacted by Congress by the simple posting of a phrase on a sign owned by a school controlled by a local school board?

[Dimensio]

>The issue is the appropriateness of the school acknowledging the existence of a God, and once doing that acknowledging a God who can be called upon through a generic statement to bless America.

You didn't answer this question earlier, so I'll post it again: How could saying/displaying "God bless America" be misconstrued by any reasonable individual as Congress making a law respecting an establishment of religion? What law is being enacted by Congress by the simple posting of a phrase on a sign owned by a school controlled by a local school board?

I don't recall that question being specifically asked to me, but my memory is poor and I often misread things.
The statement "God bless America" first and foremost implies an acknowledgement of the existence of a god of some sort. Depending on the context it could also be construed to mean a single God (capital G), which implies a monothestic worldview. A government entity making such a statement could be construed as taking the position that there exists a God and only one God (at least only one worth noting).
I'm not a lawyer and I don't claim to hold this position, so that's really the best I can explain it.