The doctrine of justification by grace alone through faith alone (sola fide) stood at the center of theological controversy during the Protestant Reformation. Men such as Luther, Melanchthon, Calvin, and Chemnitz were willing to lose their lives over the doctrine of justification, for to misunderstand this doctrine was to misunderstand the very essence of the gospel. The Protestant church appreciates these men and their convictions, but many may wonder what sola fide actually means. This article seeks to express three core components to the doctrine of sola fide: (1) that justification is forensic, not formative; (2) that justification is distinct from sanctification; and (3) that the basis for justification is the imputed righteousness of Christ. These men were convinced that it was upon these articulations that the church stood or fell, and the church today would do well to remember the urgency of this doctrine.