Of course. So should the history of Christianity, Judaism, Islam, and other religions. None of that constitutes government endorsement of religion, whereas teachers leading students in a pledge which asserts monotheism does.
Ooooh...I don't know about that. Sounds dangerous. Might foment bad thoughts in the minds of our little ones. Nasty ideas like liberty, freedom and other such things.
Of course. It is our history. Your question has nothing to do with the issues in this case.
The issue here is, can a state institution, a public school, require its employees to lead children in an endorsement of "god"?
It should be clear to everyone, regardless of your personal belief system, that it should not. That it isn't clear is a good sign that most people fail to appreciate fundamental constitutional principles.