Martin Luther's most comprehensive work on justification by faith, his commentary on St. Paul's Epistle to the Galatians is translated and edited from the Latin into a lively style, paralleling his spoken lectures. Combined with the passion and faith expressed in these lectures, the biblical foundation for the crucial doctrine of justification is underscored and expressed to a new audience. The commentary is also a historical document, a recording of a professor in a classroom in 1531 from July to December of that year, which expresses the Reformer's commitment to the good news of Jesus' death in the sinner's place, challenging the reader/hearer to compare St. Paul's theology with what he/she hears in the church today.