School children utter the phrase “one nation under God” as part of the Pledge of Allegiance. The national motto, “In God We Trust,” appears on U.S. currency. Congress and many state legislatures start their sessions with prayers, and the U.S. Supreme Court opens oral arguments with the invocation “God save the United States and this honorable court.” Most presidential inaugural addresses refer to God, and most presidents have followed George Washington's example in issuing Thanksgiving proclamations, many of which have referred to “Almighty God.”
Through these and many similar practices, the government invokes the concept of a deity. Opponents of these religious invocations say such proclamations promote religion and thus violate the First Amendment's Establishment Clause, which prohibits all laws “respecting an establishment of religion.” Defenders of governmental religious invocations, by contrast, claim that such expressions do not explicitly promote religion; rather, defenders say, religious proclamations merely acknowledge the historical and cultural connections between the United States and belief in God.
Read the full report On Ceremonial Occasions, May the Government Invoke a Deity? on the Pew Forum on Religion & Public Life Web site.