Between the fourth and sixth centuries, Christianity adapted to being a state church. The transition was not always smooth and there were tensions between the claims of the church and of the state that were never fully resolved. In spite of that, the church entered into a close and lasting alliance with the Roman state.
Since the fourth century Roman Empire, the church had been in alliance with rulers, a situation that was reinforced by the important role that some early medieval rulers had played in the conversion of their people.
The same book also shows how deeply the church became involved in politics:
... the church was the central institution of the European Middle Ages … it was a key actor in the high politics of kings and emperors; it ordered the relations of man and woman, the individual and the group, the ruler and the ruled.
Church beliefs guided by politicians
The Times Atlas of World History makes it clear that politics influenced church belief in the first few centuries of Christianity:
Meanwhile important decisions, particularly the definition of doctrine, were made by the assembled clergy. Theoretically these councils represented the voice of the Church, but in practice Christianity as the state religion was often subject to imperial constraint.
The Chronicle of the World, which portrays world history as newspaper reports, also confirms that politicians had a great influence on beliefs of the church:
Nicea, Asia Minor, 20 May 325
The Emperor Constantine, dressed in purple robes to stress the sacred nature of his power, today inaugurated the Ecumenical Council of Nicea.
What began as an academic theological debate has spread to Christian congregations throughout the empire and there is a real danger of a lasting schism. Constantine is using his skills as a peacemaker in the spiritual sphere; his advisers have devised a compromise solution which looks likely to carry the Council.
It is clear that Constantine’s main objective was to obtain an agreement to further his political aim of having a unified empire. Finding the truth of the matter does not seem to have been important.
The situation had not changed 65 years later, as is shown by the Chronicle of the World having the following report about the Roman Emperor Theodosius: