Freedom, Councils, and Schism
In the early fourth century, Constantine legalized Christianity, and the Christian population exploded from being about 10% of the Roman Empire to the vast majority of it. The church went through growing pains as it did with the first few generations of Christians, when it was no longer Jews accepting Jesus as their Messiah, but also Gentile proselytes and pagans entering into the fold. A reading of some of the bishops during the 4th century (such as St. John Chrysostom) reveals the challenges of a sometimes disorderly crowd that would enter into the church, some of whom would even get into shoving matches in the communion line in order to be first to receive.
With the persecution lifting, an abundance of highly educated citizens also entered into the church and applied their great learning to Christianity. Some of them are among the most respected saints and are still widely read today, such as the Cappadocian Fathers, while others are ranked among the heretics due to their attempts to compromise Christianity with pagan philosophy and beliefs. These heretics caused division in the church as they attempted to philosophize about God and the scriptures without the guidance of the Holy Spirit, the Scriptures, and the oral tradition that had been preserved up to that time. When their heretical ideas started to become popular, something had to be done to confront them.
The Importance of Council
When several of the greatest difficulties arose, they were settled by what is called an Ecumenical Council. I won’t go into the details of each council, but the purpose was to ensure every voice was heard, truth prevailed, and that the true Church remained united. Councils displayed a somewhat democratic process that the Church hierarchy practiced. Each bishop was in charge of a small region, and when a council was convened, bishops were summoned to represent their region. Discussions were often lively.
As a representative of his region, a bishop was accountable to both the hierarchy and laity. The final part of an ecumenical council was the return of the bishop with the council’s decision for the people to review and approve.
Power and Control
The status of being a bishop changed drastically from the time of the apostles to the fourth century church. A bishop had a nearly 100% chance of dying as a martyr during the years of persecution, but after the church was granted freedom, they became extremely influential citizens in the Roman Empire. Abuse and utilizing the bishopric for influence and power was not unheard of.
The more godly bishops used their position to guide their flock and even to keep their fellow bishops in check. There is one instance in which the Archbishop of Constantinople added to his title the word “Ecumenical,” meaning universal. Pope Gregory the Great, when he heard of this, was quite upset and wrote a scathing letter, reprimanding the Archbishop of Constantinople for placing upon himself a title that would insinuate his dominion over all other bishops. With Constantinople being the capital of the Roman Empire, the archbishop may have only been following local custom. Everyone there called themselves “ecumenical”: the librarian, the cook, the judge, etc. But Pope Gregory perceived the danger in utilizing such a title. His response confirmed that there was no universal bishop in the Christian Church. Sadly, Rome would change their ideology in later centuries.
The Great East-West Schism
Knowing about the Great Schism of 1054, aka the East-West Schism helps us to better understand what laid the groundwork for the Protestant Reformation.
The East-West Schism divided the once united  Church into the Roman Catholic Church in the West and the Eastern Orthodox Church in the East. This schism was due to several factors such as political, cultural, linguistic, and physical separation from the deterioration of the Roman Empire. However, the most significant factors were ecclesiastical and doctrinal: papal authority and a change to the Constantinople-Nicene Creed (which everyone had previously agreed not to change).
The bishop of the Roman church was always highly honored as “the first among equals,” but had no authority outside his own district. Whenever issues arose and an ecumenical council was held, every bishop had a single vote including the Roman archbishop, who was often represented by a legate due to his distance from the Eastern cities in which the councils were held.
By the 9th and 10th centuries, the Roman bishop’s power and influence had significantly grown in the West. He, as the head of the Western Church, became the anchor that held Western Civilization together during plagues, invasions, and other difficulties. Such power and influence shaped the mindset of those in the papacy so that they began to view all other bishops and archbishops throughout the world as subordinates.
This power-play became a great issue at first between Patriarch Photius and Pope Nicholas in the ninth century. Once that schism healed, again in 1054, a cardinal who supposedly  represented the Pope delivered a Papal Bull that excommunicated the Patriarch of Constantinople. This action infuriated that patriarch, and he in turn excommunicated the Pope, who had died by the time either of the excommunications were delivered.
After tempers cooled a bit, many attempts at reunion were made. The East in particular remained hopeful that differences could be worked out and a reunion reached — after all, they needed the West’s crusaders to help defend themselves against Muslim invasions.
Eastern bishops met with Western ones on a few occasions, but always encountered the same attitude from the West: we are not negotiating anything at all. You must submit to our dominance and our pope. Attempts for reunion were made until the Council of Ferrara-Florence in the 1400’s, after which the Eastern Orthodox people said they would rather submit to the yolk of the Muslims than have their faith distorted by a power-hungry pope who literally demanded all Eastern bishops kiss his feet in submission.
 I have left out the Council of Chalcedon in the 5th century and the splitting off of the “Oriental Orthodox Church.” It was a significant event, which I don’t want to belittle, but I simply don’t have the space to discuss it in any real detail in this particular blog.
 When Cardinal Humbert delivered the bull of excommunication, Pope Leo had died in captivity. Some historians believe that Humbert held a personal grudge against the Greek/Eastern people and went on his own authority after the Pope had gone into captivity. He was greeted warmly by the emperor, but was ignored by Patriarch Michael of Constantinople. The greatest reason for the deliverance of the excommunication may have been due to a personality clash between Humbert and Michael. Regardless, because Pope Leo was dead, the excommunication was technically invalid, but the harm it caused was real.