Utter nonsense. No Christian nation bans itself, by law, from calling itself a Christian nation. If you want Church and State as one, become a Muslim.There is no such thing as separation of Church and State. That is pure made up PC bullshit.
I didn't say we should call our nation a Christian nation, you did. I am interested in the freedom of expression that is in the Constitution. If students want to display a manger scene it is unconstitutional to ban them from doing so.