A book on Martin Luther hardly requires any explanation, least of all in the year 2017, which sees the quincentenary of his Ninety-Five Theses. However, given that there are already so many books on Luther, and so many published this year, the appearance of yet another might properly be thought to require some justification.
The reason for this book is quite simple. It is to explain Luther’s ideas. There are other stories to tell about Luther. The story of how a thin, anxious young man turned into a fat, complacent old man. The story of how an obscure university professor developed a commercial identity through skillful exploitation of the high-tech media of his day. But all our stories about Luther must be predicated first and foremost on his ideas, on his theology. It was Luther’s revolutionary new vision of the Christian faith that changed Christendom, Europe, and indeed the world, forever. The cataclysmic social convulsion that we label “the Reformation” was often characterized in twentieth-century history books as a matter of “great social forces.” But “great social forces” are made of people thinking the same thing, or at least of people thinking that they are thinking the same thing (which is pretty much the same thing). In the case of the Reformation, what people were thinking derived primarily from Martin Luther. Other ideas soon proliferated, by extension, imitation, or contradiction. Luther could not control the genie he had let out of the bottle, the spirit of Protestantism. The Reformation was therefore never exclusively Lutheran. But no Luther, no Reformation.
The reason for this book, then, is to explain Luther’s ideas—to explain what they were, what was distinctive about them, and how he worked them out. The task is not quite so simple as it sounds. Despite their indisputable historical significance, Luther’s ideas have never been that well understood, least of all today, in the context of a European culture busily detaching itself from its Christian roots. And even when Christianity was a more central part of European intellectual culture, Luther’s ideas were still widely misunderstood. Lutherans and others in the Protestant tradition, as insiders, were as often as not blithely unaware of what really was distinctive and different about his ideas, while Catholics and other outsiders reckoned the paradoxes that form the deep structure of his thought merely self-contradictory, and found his theology so alien to their own that they settled for at most a superficial caricature of it.
The key to Luther’s theology is his notion of certainty. Luther, who might in some ways be regarded as the intellectual progenitor of the “masters of suspicion” (Marx, Nietzsche, Freud), called a great deal into doubt. The early Luther disapproved of this pastime, but the Reformation Luther was a past master of it. Yet doubt was not his default setting. If he called things into doubt, he did so in the name of certainty. Certainty was not simply a quality his mind invested in his own ideas, a common enough foible. It was the explicit focus and priority of his interpretation of the Christian Gospel. The Bible, for him, had to be an utterly certain source of truth. The truth derived from it had, itself, to be utterly certain. And the fruit of that truth in the soul of the believer had to be an unwavering and absolute certainty of the immediate enjoyment of the grace and favor of God. This was the core meaning of his most famous slogan, “justification by faith alone.” His heart and soul demanded of Christianity something it had never before given, and to understand Luther and his ideas is to understand how he reshaped the Christian faith to yield this absolute certainty. The purpose of this book is to explain how Luther came to his revolutionary conception of Christian certainty and how that conception contradicted the traditional Christianity in which he had himself been formed.
Historical writing is a sin of omission. To make any sense of the past, one has to leave out an immense amount, and that process is as regrettable as it is inevitable. When the subject is as well documented and as relentlessly researched and commented upon as Martin Luther, then omission will be almost the defining feature of any book, especially a relatively short book. His own published writings are enough to fill a capacious bookcase. The writings of his friends, colleagues, and opponents would furnish a small library. And that is not to mention the massive body of further contemporary evidence that provides the context for the man, his ideas, and his achievement. As for the scholarly literature that has accumulated since his lifetime, it is already of such unimaginable bulk that no single human mind could cope with it in a lifetime of study. It is at least in keeping with Luther’s own method that this book is primarily the product of reading in and reflection on his own substantial output—and on the writings of his contemporaries—rather than a distillation from the humanly unassimilable mass of Luther scholarship. Luther spoke of deriving Christian truth from the Bible alone. This was at best an exaggeration, and I do not claim to derive my understanding of Luther from Luther alone. But Luther’s own writings are the starting point and reference point for this investigation. Historical writing is, to repeat, a sin of omission. But if, as Luther taught, even the best of human works and actions is still a sin, then perhaps this historian can legitimately hope that his work, however deficient, may nevertheless have some good in it.
It is customary at this point in a preface for authors to remark that, whatever help and advice they might have received from other people in the writing of their book, any mistakes that remain are emphatically their own. In this case, the familiar refrain has even more truth than usual. There really is hardly anyone else to blame. I must therefore do the decent thing and accept full responsibility for what follows. Apart from the two anonymous readers who scrutinized the text on behalf of Princeton University Press, the only other people who have read any of this are my student Jonathan Reimer and my son Oliver. I am deeply indebted to the two anonymous readers, who were generous with both encouragement and constructive criticism, and saved me from myself on numerous occasions. Jon Reimer kindly gave some time, after the successful completion of his doctoral dissertation, to a close reading of the opening chapter, and was especially helpful in tracking down some particularly recondite references. He also compiled the index. Olly heroically worked his way through most of the book in the narrow window of opportunity between completing his education and commencing gainful employment. His cheerful approbation was, as ever, a tonic at a time when stress over a rapidly receding deadline threatened to get the better of me. It is to Olly, therefore, that this little effort is gratefully dedicated.