The Holy Bible is the final authority in all matters of faith and practice for Reformation Christians. The Augsburg Confession is the doctrinal confession of faith adopted by the Lutheran Church. It is part of the Book of Concord, which includes the three ancient ecumenical creeds: the Apostles’ Creed, the Nicene Creed, and the Athanasian Creed. It also contains the Apology of the Augsburg Confession, the Smalcald Articles, the Treatise on the Power and Primacy of the Pope, Luther’s Small and Large Catechisms, and the Formula of Concord. (reference)
Martin Luther wrote the Catechisms and the Smalcald Articles. Phillip Melanchthon wrote the Augsburg Confession, its Apology, and the Treatise. So, Melanchthon wrote more of the Lutheran doctrines than Martin Luther. Note that the other writings of Luther have no official status among Lutherans, although most of them make for sound reading.
The Augsburg Confession was written in a particular historical context in which the Lutheran movement attempted to explain and justify itself to the religious and civil authorities of the day, notably Emperor Charles V of the Holy Roman Empire, at the Diet of Augsburg on June 25, 1530. Although reconciliation did not happen, the Augsburg Confession provided the primary confession of the Lutheran movement.
The twenty-eight articles in the Augsburg Confession consist of twenty-one statements of doctrine and seven declarations about abuses, and demands for reforms. Although Melanchthon and his associates compiled the confession, Luther approved it as an accurate account of his doctrine.