Christendom: The Triumph of a Religion, AD 300-1300

Image of Christendom: The Triumph of a Religion, AD 300-1300
Release Date: 
April 4, 2023
Reviewed by: 

“This is a very dense volume, filled with detailed discussion on complicated issues of dogma, politics, and the incorporation of Christianity into European society writ large.”

How did Christianity become the dominant faith and societal force in Medieval Europe? How did it evolve, and who were the key figures in its rise? These are questions tackled by Peter Heather in this new book that covers the critical 1000 years from the rise of Constantine to the era of the Fourth Crusade and the Fourth Lateran Council.

In his foreword the author, a self-described elapsed Anglican, lays out his thesis offering a more secular look at Christianity as a social, cultural, and political phenomenon versus looking at it through the lens of faith. What makes this an interesting thesis is the author spends numerous chapters detailing how doctrines, practices, and canon law developed, from the evolution of Christian beliefs on the divinity and humanity of Christ during the first four centuries of Christianity to the development of many of the practices and dogmas of the faith still in use by millions of Christians today.

Beginning with the conversion of Constantine through his vision of the Cross of Christ before the Battle of the Milvian Bridge in 312 that furthered his control of the Roman Empire, the author examines how either Rome was Christianized, or Christianity was Romanized depending on your point of view for the next several centuries. While the Edict of Milan in 313 ended the government sponsored persecution of Christians, the new faith still spread very slowly, and as the author argues, its eventual dominance over pagan Roman gods was not assured.

This is a common theme throughout the first third of the book as Christianity slowly spread throughout the empire, especially after Constantine founded his own city that bore his name, becoming first acceptable to the ruling elites before dispersing to the general population. This pattern continued as Christianity continued to spread through first the British Isles, then the rest of Europe after the overthrow of the last Roman Emperors in 476 CE. As new monarchies emerged in Western Europe, monks and other evangelizers spread the faith first to the rulers of new regions, replacing pagan gods and festivals with holy days dedicated to Christian martyrs before establishing a presence throughout the new territory.

Along the way there were plenty of controversies and intrigue within the emerging church hierarchy, with the arguments over the question of the divinity and humanity of Jesus ranging for over a century and occupying the first great church councils of Nicaea and Constantinople. Once this issue was finally settled—and the author makes a compelling case that the eventual doctrine of the Nicaean Creed recognized by all major denominations of Christians was far from certain—the major challenge became the still controversial question of the relationship between church and state.

In particular, the church hierarchy would spend a great deal of energy for hundreds of years with first the Roman emperors and then their monarchical successors as they contested who could appoint bishops and handle other ecclesial decisions. As new dynasties formed this relationship was finally settled as a strengthening papacy finally gained the upper hand in this power struggle that would determine the fate of kingdoms and the eventual independence of the church.

As these arguments continued, other forces arose to challenge the now dominant religion of Europe, particularly the rise of Islam and the loss of much of the Mediterranean basin and the old Byzantine empire to a new faith that began the conversion of its new subjects. This led to several chapters on the Crusades and an examination of the political impact of the growing power of an increasingly independent papacy able to wield enormous influence by calling on the monarchs and nobility to Europe to liberate the Holy Land and spread the faith, often at sword point, to the eastern frontier of Europe.

Finally, the author ends the volume with an examination of the darker side of Christianity during the rise, exploring the rise in antisemitism and the complicated relationship of the Church with women, from controversies about women lay leadership to the eventual rise in the primacy of the Virgin Mary in Christian dogma and faith practices. And of course, the most critical event of the final two centuries covered in this volume, the rise of the Franciscans and Dominicans who were among the first great formal religious orders sanctioned by the Pope to help spread the faith.

This is a very dense volume, filled with detailed discussion on complicated issues of dogma, politics, and the incorporation of Christianity into European society writ large. It is a fascinating contrast to traditional histories of Christianity written by Catholic or authors of other denominations.