"Concerning Christian Liberty; with Letter of Martin Luther to Pope Leo X." by Martin Luther is a treatise written in 1520. As the third of Luther's major reforming works that year, it explores a revolutionary concept: Christians, as forgiven children of God, are no longer compelled to keep God's law for salvation, yet freely choose to serve God and their neighbors. Luther develops his doctrine of justification by faith, declaring that a Christian is simultaneously the "most free lord of all" and the "most dutiful servant of all." (This is an automatically generated summary.)