The Augsburg Confession, also known as the Augustan Confession or the Augustana from its Latin name, Confessio Augustana, is the primary confession of faith of the Lutheran Church and one of the most important documents of the Lutheran Reformation. The Augsburg Confession was written in both German and Latin and was presented by a number of German rulers and free-cities at the Diet of Augsburg on 25 June 1530. The Holy Roman Emperor Charles V had called on the Princes and Free Territories in Germany to explain their religious convictions in an attempt to restore religious and political unity in the Holy Roman Empire and rally support against the Turkish invasion. It is the fourth document contained in the Lutheran Book of Concord.
On 21 January 1530, Emperor Charles V issued letters from Bologna, inviting the Imperial Diet to meet in Augsburg on 8 April for the purpose of discussing and deciding various important questions. Although the writ of invitation was couched in very peaceful language, it was received with suspicion by some of the Protestants. Landgrave Philip of Hesse hesitated to attend the diet, but the Elector John of Saxony, who received the writ 11 March, on 14 March directed Martin Luther, Justus Jonas, Johannes Bugenhagen and Philipp Melanchthon to meet in Torgau, where he was, and present a summary of the Lutheran faith to be laid before the Holy Roman Emperor at the diet.