On the Freedom of a Christian
On the Freedom of a Christian (Latin: "De Libertate Christiana"; German: "Von der Freiheit eines Christenmenschen"), sometimes also called "A Treatise on Christian Liberty" (November 1520), was the third of Martin Luther’s major reforming treatises of 1520, appearing after his Address to the Christian Nobility of the German Nation (August 1520) and the work Prelude on the Babylonian Captivity of the Church (October 1520). The work appeared in a shorter German and a more elaborate Latin form. There is no academic consensus whether the German or the Latin version was written first. The treatise developed the concept that as fully forgiven children of God, Christians are no longer compelled to keep God's law; however, they freely and willingly serve God and their neighbors. Luther also further develops the concept of justification by faith. In the treatise, Luther stated, "A Christian is a perfectly free lord of all, subject to none. A Christian is a perfectly dutiful servant of all, subject to all." 
- Reinhold Rieger: Von der Freiheit eines Christenmenschen, De libertate Christiana, Mohr Siebeck, Tübingen 2007, p. 5-12.
- Albrecht Beutel, "Luther's Life," tr. Katharina Gustavs, in The Cambridge Companion to Martin Luther, ed. Donald K. McKim (New York: Cambridge University Press, 2003), 11.