Two interrelated questions revolve at the core of the controversies that Martin Luther engaged in, questions he came back to again and again: the problem of authority and what is meant by “Word of God.” Luther’s involvement in these debates was spectacular, issuing in a torrent of pamphlets and treatises that are a trove for our study. Correlative to the question of the Word of God and what God has purportedly said is the question of how human beings–Christians in particular–ought to live. In this way, the question of authority and the Word of God is of paramount importance for American evangelicals. In this paper I propose to contrast the dominant evangelical fundamentalist understanding of “Word of God” with that of Martin Luther as found in his works “A Brief Instruction on What to Look for and Expect in the Gospels,” “Concerning Christian Liberty,” “Concerning the Letter and the Spirit,” and “Letter on Translating the New Testament,” among others. I will then evaluate the implications of these respective views on how 21st Century American Evangelicals should live faithfully in this day.