"The Bondage of the Will is fundamental to an understanding of the primary doctrines of the Reformation. In these pages, Luther gives extensive treatment to what he saw as the heart of the gospel. Free will was no academic question to Luther; the whole gospel of the grace of God, he believed, was bound up with it and stood or fell according to the way one decided it... This is the greatest piece of writing that came from Luther's pen. In its vigour of language, its profound theological grasp, and the grand sweep of its exposition, it stands unsurpassed among Luther's writings" (front and back cover).
Luther here refutes the Romish notion of "free will" in man and upholds the absolute sovereignty of God in the salvation of sinners -- as well as justification by faith alone.
In this book he replied to the Roman Catholic scholar, Erasmus, and his diatribe The Freedom of the Will. Though disagreeing with just about everything else Erasmus wrote, Luther commended Erasmus for recognizing the crux of the matter at issue between Rome and the Bible believers, the debate over "free will."
"This book is most needful at the present day," noted Atherton in 1931, for "the teachings of many so-called Protestants are more in accordance with the Dogmas of the Papists, or the ideas of Erasmus, than with the Principles of the Reformers; they are more in harmony with the Canons and Decrees of the Council of Trent than with the Protestant or Reformed Confessions of Faith."