A complex process of transformation creating the breakthrough into the modern age, with effects that are still formative today, took place in the history of the Western church in the seventeenth and eighteenth centuries. The most important semantic elements in it, which gradually separate out into the Age of Denominations, Pietism and Enlightenment, describe three forms of Christian life and thought that overlap in many ways and only produce a sufficiently nuanced overall picture of early modern church history when viewed as forming a complete whole. This first sub-volume discusses the development of a denominationally plural Christianity in Europe in the Age of Denominations.