Shearn combines his intensive knowledge of German, philosophic theology with untranslated early German works of Paul Tillich to present in English Tillich's early work on the theme of justification of the doubter. He has three types of readers in mind: theologians interested in early twentieth-century theology, advanced students of Tillich who lack sufficiency in the German language, and those proficient in German but who have not mastered the early German sermons. His title of pastor indicates how heavily the work depends on Tillich's early sermons mostly unknown to the English speaking world.

The theme of justification of the doubter holds the dissertation together, while the form of a dissertation and his notes assures the academic rigor of the book and also gives it religious interest. Tillich's own doubts, and the doubts of the modern-academic Christian reader are presupposed. American Christians probably are less doubtful than Tillich presupposed in his later work or Shearn with his English and German experiences may assume. Most American theological students or university students will find the dissertation too difficult to follow. Further modification of the dissertation could have moved it toward a more readable book; presently, it is midway between the dissertation and a book, and the author refers to it as both dissertation and book. Readers of the North American Tillich Society will appreciate the work, and perhaps some of the Society's publications could have aided Shearn's argument. Perhaps because academic audiences and church members have different expectations that shape the presentations offered to them, the dialectic between them is hard to maintain. Perhaps the political context of the empire, his father's role in it, and the meaning of the war means that more considerations should have been given to the war sermons to the troops. The references to his father and their letter exchanges are a major contribution of the book. The migration from a conservative theological ethic to a socialist perspective needed more consideration.

The dissertation is beautifully organized with most chapters having an introduction and a conclusion. The introduction is a guide to the whole book except for an inadequate brief comment of a few paragraphs on Tillich's sex life that explores Tillich and Niebuhr in a couple of sentences with an unfortunate comment by Richard Fox, who knew neither of them and who was a major biographer of Reinhold Niebuhr. The conflict Fox reports between them is without a source. The lifelong correspondence between the two theologians actually reveals their continued respect and friendship for each other.

Chapter 2 presents an analysis of Rechtfurtigung und Zweifel (1919), which is the concluding text of his research as a paradigm for the problem of justification and doubt and the premise of Tillich's development. Chapter 3 traces Tillich's intellectual development from 1904 to 1909 and challenges Tillich's autobiographical writings for this period. Chapter 4 considers Tillich's faith in Lichtenrade and focuses on how he changed an undelivered sermon from despair to assurance before preaching it on Easter Monday. Chapter 5 is on Tillich's use of Schelling in his two dissertations. American students who have had these dissertations for years in Nuovo's translations could benefit by comparing Schern's work to their own conclusions. Chapter 6 examines the sermons from Nauen (1911–1912) criticizing creed believers but regarding conservatives as self-righteous and criticizing the liberals. Chapter 7 moves to the Moabite sermons and notes the worker's domination of Moabite and Tillich's attempts to answer doubt with Christology. Chapter 8 analyzes Tillich's early systematic and moves toward universal salvation. Chapter 9 studies Tillich's sermons in World War I and basically excuses his nationalistic martyrdom theology on the basis of loyalty to the empire, which is undergoing change. His presentation of context for the sermons is helpful, but work in the North American Society has been more critical of his religious jingoism. Chapter 10 is basically a conclusion of the book outlining Tillich's evolution on the justification of the doubter. The presentations and interpretations of the translation of all of this newly published archival material is a valuable contribution to the scholarship on Tillich.

The beginning of the book with a repudiation of Luther's declaration regarding belief, faith, and justification, and the conclusion that “we may well wish that religious doubt would increase” provides little help to the churches and obscures the reality of religious revival in Asia, Africa, and changes in South America. Tillich also failed to appreciate how the masses of religious people could sustain themselves religiously without major regard for the criticisms of modernity's science.