The deepest theological danger inherent in American exceptionalism, then, is that of the messiah nation that does not simply seek to follow God's will, but acts as a kind of substitute God on the stage of history. When the concept of chosenness becomes unmediated by the church and unmoored from the biblical narrative, the danger is that the nation will not only be substitute church but substitute God. When the shrine is emptied of the biblical God and replaced with a generic principle of transcendence, there exists the danger that we will not come to worship God, but will worship our freedom to worship God. The empty shrine is surreptitiously filled. Our freedom itself becomes an idol, the one thing we will kill and die for.
William T. Cavanaugh, "Messianic nation: A Christian theological critique of American exceptionalism", University of St. Thomas Law Journal, Vol. 3, issue 2, article 6 (Fall 2005), 268. Read PDF article.