Pledge of Allegiance
From Iron Chariots Wiki
The pledge of Allegiance is relevant in that in 1954 the words "under God" were added. This is often referenced by apologists as evidence that America is a Christian Nation.
9th Circuit decision in Newdow v. Elk Ridge
To recite the pledge is not to describe the United States; instead it is to swear allegiance to the values for which the flag stands: unity, indivisibility, liberty, justice and -- since 1954 -- monotheism