Christian Nationalism presents an existential threat to both Christ's church and American democracy. Now is the time -- before it is too late -- to reckon with all the places its pernicious influence arises. On full display in recent elections, Christian Nationalism also exists in sanctuaries where an American flag has been displayed for decades, when we pledge allegiance to one nation "Under God," or when the U.S. is called a Christian nation. Baptizing America critiques the concept of civil religion, arguing that such expressions are far more dangerous than we realize. Mainline Protestant congregations will likely recognize themselves in the overlooked expressions of Christian Nationalism that pop up in the activities of both church and state.