Many scholars assume that Luther advocates for a Christian life in which human beings are always passive recipients of God's grace as it is delivered in preaching, and mere instruments through which God works to serve their neighbors. This book offers a different reading of Luther's views on human agency by drawing on a fresh source: Luther's preaching. Drawing on Luther's sermons in the Church Postil as a primary source, Justin Nickel argues that Martin Luther preached as though Christians have real, if secondary, agency in the lives they lead before God and neighbor. As a result, Nickel presents a Luther substantively concerned with how Christians lead their lives.