Historians and theologians have long recognized that at the heart of the sixteenth-century Protestant Reformation were five declarations, often referred to as the "solas": sola scriptura, solus Christus, sola gratia, sola fide, and soli Deo gloria. These five statements summarize much of what the Reformation was about, and they distinguish Protestantism from other expressions of the Christian faith. Protestants place ultimate and final authority...