Were There Churches of Christ in the Middle Ages?
Some Christians claim the modern Church of Christ was founded in AD 33 and has continued ever since. This historical claim denies the importance of the early 1800s Stone-Campbell Restoration Movement in the formation of our fellowship. However, the historical problem with this claim is immense. Most Church of Christ members admit that all commonly accepted histories of the Church of Christ tie it to the Restoration Movement. There is no generally accepted historical evidence that we existed in any recognizable form before 1800.
For those hoping to prove the Churches of Christ extend back to AD 33, there's an approximately 1,400 year gap from the Council of Nicaea to the Restoration Movement that must be accounted for. Where was the Church of Christ during that era?
It's possible to find groups of Christians who resemble us dating back to Luther due to the diversity and chaos produced by the Reformation. However, the real historical problem is the pre-Reformation period that extends for more than a millennia through the Middle Ages.
Various groups have been suggested as possible proto-Churches of Christ during this period, but for various reasons I don't think any of them had much similarity with our modern fellowship. Hans Grimm, in his essay Tradition and History of the Early Churches of Christ In Central Europe, argued that the Prescillians, Paulicians, Bogomils, the Pataria, Cathars, and Waldensians were identical to the modern Churches of Christ. The evidence, however, suggests otherwise.
PRESCILLIANISM
Priscillianism was founded by a wealthy noblemen in Spain who lived in the late 300s. He taught that Christians should attain perfection via asceticism, and that to achieve this perfection one couldn't get married. If a follower was already married they were instructed to stop having sex with their spouse. He divided Christians into three orders: apostles, prophets, and doctors (doctors being the highest). The Priscillians also practiced numerous odd variations like taking the Communion bread/wine home before eating it rather than sharing it at church. It's difficult to imagine Prescillianism as having much continuity with the modern Churches of Christ. It's followers were dedicated to a monastic way of life that emphasized extreme fasting and self-denial.
THE PAULICIANS
The Paulicians were a Gnostic sect that was most active from the 600s to the 800s. They believed that an evil god created the world, and that Jesus came to earth to help free men from their corrupt bodies. They rejected the canonicity of the Old Testament, First & Second Peter, and Revelations. A fragment of their writings taught that Adam ad Eve's first sin was a blessing in disguise. How many modern Churches of Christ teach that the world was created by an evil deity? None. The Paulicians definitely don't constitute an early Church of Christ fellowship.
BOGOMILISM
The Bogomils originated in the 900s in Bulgaria. They emerged out of the Paulicians and taught similar Gnostic and dualist doctrines. The Bogomils believed that God had two sons. The older son became Satan and the younger son, Michael, came to earth as Jesus. Each Bogomil community was overseen by twelve "apostles." The Bogomils had many other strange practices and beliefs, but the ones I've listed above already disqualify them from any association with the modern Churches of Christ.
THE PATARIA
The Pataria, or Patarini, were a group of Catholic reformers in the 1000s. They wanted to root out corruption in the Catholic Church. They were especially supportive of papal reforms and were characterized by piety. There's little reason to associate them with the Church of Christ. They were basically just Catholic reformers.
CATHARISM (THE ALBIGENSIANS)
The Cathars/Albigensians were a neo-Gnostic dualist group in France and Italy between the 1100s and 1300s. They likely traced their spiritual heritage back to the Paulicians and Bogomils. Like other Gnostic groups, they believed in two gods: an evil Old Testament god and a good New Testament god. They believed the physical world was equivalent to Satan. The Cathars were eventually destroyed by the Catholic Church after a particularly bloody crusade that allegedly resulted in over a millions deaths.
THE WALDENSIANS
The Waldensians were founded by Peter Waldo in the 1100s as an ascetic movement that taught that poverty was a path to spiritual perfection. It was nearly annihilated by the Catholic Church but eventually joined the Reformation and continues today as a denomination. The group met on Saturday instead of Sunday. The Waldensians are now explicitly Calvinist.
Of the six possible candidates mentioned by Hans Grimm as medieval Churches of Christ the only one that even remotely resembles us is the Waldensians. However, considering that the Waldensians still exist as a non-Church of Christ denomination there's really no reason to assume they represented a medieval Church of Christ. Modern Churches of Christ have as much in common with the Waldensians as with any other random Protestant denomination.
CONCLUSION
While it remains possible that there were Churches of Christ operating during the Middle Ages, the historical evidence provides no proof supporting this theory. The vast majority of the medieval population had no access to a Bible, and few possessed the ability to read one even if they'd had it. Given these historical circumstances, it remains difficult to imagine a Bible centered Church of Christ like groups emerging during the over one thousand years extending from the Council of Nicea to the invention of the printing press and Reformation. Historically speaking, all modern Churches of Christ, and affiliated institutions, have known roots leading back to the American Restoration Movement; and thus for all practical historical purposes our modern fellowship began there. Please comment below if anyone reading this has evidence to the contrary.