series of lectures he gave between 1513 and 1517. Yet at the same time that he moved from a new understanding of the righteousness of God and to an altered appreciation of the role of works in the life of a Christian, he also touched on one more critical and related issue. In doing so, he changed his understanding of the nature of a Christian and therefore of the nature of the church itself. Late medieval theologians had defined a true Christian as someone who, besides having faith, was in some sense