Christianity had transformed greatly throughout the first millennium of its existence along with the changing political culture of Europe. The collapse of the Roman Empire in the fourth and fifth centuries gave rise to an increasingly powerful and influential Church that would remain so for five hundred years. However, the onset of the feudal mutation and the collapse of imperial and royal power in Europe in the tenth century led to the division and subjugation of the Church.
Christianity transformed from a persecuted, unorganized group of believers into a hierarchical, dominating Church over the course of seven centuries, developing alongside the changing political environment of post-Roman Europe. The development of the institution of the Catholic Church and the spread of Christ throughout Europe during these seven centuries directly impacted every aspect of late-antiquity and early-medieval life, especially politics and the relationship between kings and religion. During this time period the Church rejected its domination by the Roman and Byzantine emperors, in turn exerting its own type of spiritual dominance over the rulers of post-Roman Europe. Christianity, through the Church, became organized and “conquered” all of Europe by the time of the Norman Conquest of England in 1066.
Christianity had developed as a religious idea in Roman Palestine, and had slowly spread throughout the eastern part of the Empire toward the west. During the first three centuries of its existence, Christianity remained disorganized and concentrated within the cities. Each group of believers centered on a few charismatic local leaders and developed their own liturgy. However, the conversion of Emperor Constantine in AD312 changed the structure of Christianity and turned it into a well-organized, quasi-political institution. The Church provided Constantine with a tool to use to hold together the crumbling Empire. The Church came under the Emperor’s control with the Emperor as the “Divus Caesar”, or divine emperor. Constantine used the Christian bishops as imperial officials to administer law and justice throughout the Empire. These “imperial bishops” answered directly to the Emperor, thus instituting imperial dominance over the Church. The Council of Nicaea in AD325 further brought the Church under imperial control with the establishment of a uniform liturgy to use throughout the Empire and approved by the Emperor.
The Western Roman Empire gradually collapsed during the fourth and fifth centuries to be replaced by “barbarian” kingdoms that thought of themselves as “Roman” and maintained many of the classical Roman institutions. The political structure and culture of the new kingdoms was different, however. Germanic kings with long hair and animal skins took the place of the emperors. These barbaric kings had been converted to Christianity during the Roman Empire by missionaries, but practiced Arianism rather than Roman Catholicism. Christianity continued to thrive under the Germanic kings, spreading the religion through Western Europe. In AD508, Clovis of the Franks converted to Christianity followed by his warriors and subjects. He was followed by the Visigoth king, Recurred in AD589 by the conversion of Ireland during the sixth century. Under the Germanic kings, the Christian bishops became the predominant source of continuity between the Empire and the Germanic kingdoms. The bishops also became a source of great power in the post-Roman kingdoms. Germanic kings used the bishops as a link between the king and the Roman citizens living in the kingdom. The bishops grew very powerful serving as the representative of the largest class of subjects. The kings recognized this power and acknowledged it by granting the bishops political power to administer to the needs of the former Romans. Monasteries also became important institutions for the Germanic kings. The monasteries became centers of culture,