What do we stand for?

Former British Prime Minister Margret Thatcher said "You use the name of Deity in the Declaration of Indepence and in the Constitution of the United States, and yet you cannot use it in the schoolroom." We live in a country that was founded on belief in God. Why can we not mention the very principles this great nation was founded on in the classroom? One of the mottos of this country is "In God we Trust", yet we cannot even mention his name in secular settings. We say we trust in God and we swear by him in our court system, but it seems we have abandoned him in all other aspects.