Björn Slenczka's dissertation, defended at Humboldt University in Berlin under the supervision of Dorothea Wendebourg, focuses on the inner-evangelical dynamics resulting from the differences of opinion at the second imperial Colloquy of Worms, which took place in the autumn of 1557. The meeting was meant to provide a platform for discussing questions causing disagreement between Roman Catholic and evangelical theologians, with the hope of finding consensus and reaching unity. Among those representing the Church of Rome were Julius Pflug, Petrus Canisius, Michael Helding, Friedrich Staphylus and two Leuven professors, Tiletanus and Rythovius. The adherents of the Augsburg Confession present at the discussions included delegates from Albertine and Ernestine Saxony, Württemberg, Hesse, Brandenburg, Pomerania and other places, who held diverse positions on a number of matters. Within this heterogeneous group were Melanchthon and a number of his followers, the so-called Philippists, with at least six Gnesio-Lutheran-oriented theologians on the opposing side and a few, such as Johannes Brenz, who did not clearly belong to either camp. Highlighting the already existing inner-Protestant disagreements and how they unfolded at Worms guides Slenczka's investigation. His contention that they resulted in a schism, which ultimately led to the breakdown of the colloquy, makes up the central argument of the book.

Slenczka's monograph aims to challenge existing interpretations of the developments at Worms on various levels. On the one hand he argues for a terminological re-categorisation of the colloquy as an imperial religious disputation (Reichsreligionsgespräch) instead. He also issues a call for the reconsideration of and a more precise approach to the role and impact of Matthias Flacius Illyricus’ theological positions and that of a Gnesio-Lutheran group at Worms vis-à-vis the delegates. Previous scholarship has either held Flacius responsible for the failure at Worms, or praised him for saving the Lutheran reformation. Slenczka sets out to demonstrate that neither of these is true. He points out that Flacius did not have the final say in shaping the expert opinion (Gutachten) written for the delegates from Ernestine Saxony, nor was he able to steer the flow of the discussions from behind the scenes through correspondence with the participants in Worms or at the Weimar ducal court. This is attributed to the fact that Flacius had only been in Jena as professor for a few months and was not yet well established in the territory, so his theological stances did not prevail. Throughout the text, Szlencka accentuates the inner-evangelical process of the pluralisation of ideas that began after Luther's death, finding its culmination in the schism of Worms. By studying several primary documents in detail, Szlencka offers a more nuanced reading of the theological viewpoints represented by the key individuals and groups at the colloquy than previous works on the subject have done. Some of these sources reveal what was taking place in the background, shedding light on the power dynamics and the many different agendas that were present. Overall, the book is well-written and minutely researched. Particularly helpful are the appendices and the five different indices. The new insights offered by Slenczka make this work a valuable contribution to the study of confessional politics and attempts at theological consensus-building in the sixteenth century.