Lutheranism is one of the largest branches of Protestantism that identifies with the teaching of Martin Luther, a 16th-century German reformer. Luther's efforts to reform the theology and practice of the church launched the Protestant Reformation. The reaction of the government and church authorities to the international spread of his writings, beginning with the 95 Theses, divided Western Christianity.
The split between the Lutherans and the Catholics was made public and clear with the 1521 Edict of Worms: the edicts of the Diet condemned Luther and officially banned citizens of the Holy Roman Empire from defending or propagating his ideas, subjecting advocates of Lutheranism to forfeiture of all property, half of the seized property to be forfeit to the imperial government and the remaining half forfeit to the party who brought the accusation.
The divide centered primarily on two points: the proper source of authority in the church, often called the formal principle of the Reformation, and the doctrine of justification, often called the material principle of Lutheran theology.[a] Lutheranism advocates a doctrine of justification "by grace alone through faith alone on the basis of Scripture alone", the doctrine that scripture is the final authority on all matters of faith. This is in contrast to the belief of the Roman Catholic Church, defined at the Council of Trent, concerning authority coming from both the Scriptures and Tradition.
Martin Luther always disliked the term Lutheran, preferring the term Evangelical, which was derived from εὐαγγέλιονeuangelion, a Greek word meaning "good news", i.e. "Gospel". The followers of John Calvin, Huldrych Zwingli, and other theologians linked to the Reformed tradition also used that term. To distinguish the two evangelical groups, others began to refer to the two groups as Evangelical Lutheran and Evangelical Reformed. As time passed by, the word Evangelical was dropped. Lutherans themselves began to use the term Lutheran in the middle of the 16th century, in order to distinguish themselves from other groups such as the Anabaptists and Calvinists.
In 1597, theologians in Wittenberg defined the title Lutheran as referring to the true church.