In my 2015 Pickwick published book – The wheat and the tares – a variety of answers were set out and examined around late mediaeval and early modern ecclesiology (that is, doctrines of what constitutes the ‘church’). This new textbook, a companion volume, will focus on the equally important, but surprisingly little considered, question of what is/was the correct relationship between the ‘church’ (as understood under differing sectarian guises) and the ruling magisterial authority/power (from the city council to the king). For example, we know from the previous volume what the Church was in Luther’s doctrine. Here, we will examine how that Church relates to, or fits in with, or is separate from, or was controlled by the temporal government of the realm in which it was located. Working out the relationship between the Church and the state is one of the key tension-producing causes of late mediaeval period and, as such, it deserves a great deal more attention than it has garnered in modern scholarship. After all, the various attempted resolutions to this (and other key questions) not only set into motion what came to be known as the Reformation, but also determined the social, political, economic and philosophical understandings found in modern Western societies’ determination to keep the Church and the state in well-defined autonomous cubicles. Set into the context of related doctrines, such as ecclesiology, salvation theology, conciliarism, the divine right of kings, and many others, this new book pinpoints how and why differing theories developed independently, dependently, or mutual opposed. Starting from a common scripture and history (sacred and secular) this book examines how the surety of the Roman Catholic Church (and its claims to supersede and therefore control all temporal authorities) began to break down in the face of serious doubts and hard questions from emerging thinkers. Why this happened was due to both the spread of new and exciting ideas and new interpretations of the traditional body of evidence. Together, these ushered into existence rival ideas within the Church (e.g., conciliarism v. papal supremacy) as well as rival regional claims (e.g., Luther’s two kingdoms doctrine v. Bucer’s co-terminism). This book examines, compares, and explains these new theories, ranging from Erasmus, through Luther, to men as diverse as John Knox, Peter Martyr Vermigli, Richard Hooker, and Melchior Hoffman (to name but a few). It takes into account regional variations, cross sectarian influences, scriptural interpretations, the rule of Christ (discipline and the ban), sola scriptura, and adiaphora (things indifferent to salvation) and how these ideas were taken up, challenged, and shaped by the major and some minor thinkers in the dynamic, confessional and dogmatic phases of the Reformation.