Byzantine Emperor Basil II "The Bulgar Slayer"
The Emperor Basil I, who usurped the throne in 867, attempted to clarify relations between Church and State. In his update of the Byzantine legal codes, Basil affirmed that “the peace and prosperity of the citizens, in body and soul, depends on the concord of the kingship and the priesthood.” Basil, however, made a sharp break from the policies of nearly all of his predecessors. As Runciman writes, Basil’s law code “gives no precedence to the kingship. He raises the Patriarch to be in effect the equal partner of the Emperor.”
Relations between Church and Emperor soured under Basil’s son Leo VI. Leo’s first three wives each died while still young, and none provided him with an heir. When Leo sought the blessing of Patriarch Nicholas for a fourth marriage, the Patriarch refused. The crisis lasted for some time until Leo, with the blessing of the Pope of Rome, deposed Nicholas and replaced him with a more pliant Patriarch. But after Leo’s death, his successor Alexander restored Nicholas to the Patriarchate. When Alexander died soon afterward, Nicholas became head of a Regency council for Leo’s young son Constantine VII. During this time, Nicholas ran the government and was Emperor in all but name. However, neither the ruling class nor the populace liked to see a cleric exercising secular power, and less than a year after Alexander’s death, Leo’s wife Zoe replaced Nicholas as regent, strictly warning the Patriarch to limit himself to Church affairs. Despite this rebuke, however, the Church’s power vis-à-vis the state had never been higher.
But this triumph was not to last. The strong Emperor Basil II reasserted Imperial control over the church, even leaving the Patriarchate of Constantinople empty for five years. In 1054, Basil’s eventual successor Constantine IX made the fateful decision to appoint Michael Cerularius as Patriarch. The ambitious Michael worked hard to increase the power of the Patriarchate at the expense not only of the State, but also over the rest of the Church. At the same time that Constantine was trying to improve relations with the Pope, Michael took several anti-Roman actions that led ultimately to a break in communion at 1054. As Runciman comments, the events that led to the Great Schism
Showed that where politics were intermingled with a religious issue a Patriarch who was sure of popular support could defy the Emperor and ruin Imperial policy. But…Cerularius found that when he tried to interfere in purely political matters he lost popular support…the career of Cerularius showed both the power and the limitations of the Patriarchate.