Konkordienformel
The "Augsburg Confession" has singular importance A recent book on Lutheranism asserts, "To this day ... the Augsburg Confession ... remains the basic definition of what it means to be a 'Lutheran.'""The Apology", the "Smalcald Articles", the "Treatise", and the "Formula of Concord" explain, defend, or serve as addenda to "The Augsburg Confession."