A Treatise on Christian Liberty is one of Martin Luther's major reforming treatises of 1520. It 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."