Lutheranism is a major branch of Western Christianity that identifies with the theology of Martin Luther, a German reformer. Luther's efforts to reform the theology and practice of the church launched the Protestant Reformation. Beginning with the 95 Theses, Luther's writings disseminated internationally, spreading the ideas of the Reformation beyond the ability of governmental and churchly authorities to control it.

Traditionally, Lutherans hold the Bible of the Old and New Testaments to be the only divinely inspired book, the only source of divinely revealed knowledge, and the only norm for Christian teaching. Scripture alone is the formal principle of the faith, the final authority for all matters of faith and morals because of its inspiration, authority, clarity, efficacy, and sufficiency.

The authority of the Scriptures has been challenged during the history of Lutheranism. Martin Luther taught that the Bible was the written Word of God, and the only reliable guide for faith and practice. He held that every passage of Scripture has one straightforward meaning, the literal sense as interpreted by other Scripture.[clarification needed] These teachings were accepted during the orthodox Lutheranism of the 17th century. During the 18th century, Rationalism advocated reason rather than the authority of the Bible as the final source of knowledge, but most of the laity did not accept this Rationalist position. In the 19th century, a confessional revival reemphasized the authority of the Bible and agreement with the Lutheran Confessions.^[1]