Overview

Papal supremacy is the doctrine of the Roman Catholic Church that the pope, by reason of his office as Vicar of Christ and as pastor of the entire Christian Church, has full, supreme, and universal power over the whole church, a power which he can always exercise unhindered—that, in brief, "the Pope enjoys, by divine institution, supreme, full, immediate, and universal power in the care of souls."

The doctrine had the most significance in the relationship between the church and the temporal state, in matters such as ecclesiastic privileges, the actions of monarchs, and even successions. The creation of the term "papal supremacy" dates back to the 6th century, at the time of the fall of the Western Roman Empire, which was the beginning of the rise of the bishops of Rome to not just the position religious authority, but the power to be the ultimate ruler of the kingdoms within the Christian community (Christendom), which it has since retained.

The Church and the Roman Empire

In the early Christian era, Rome and a few other cities had claims on the leadership of the worldwide church. During the 1st century of the church (c. 30–130), the Roman capital became recognized as a Christian center of exceptional importance. In the late 2nd century CE, there were more manifestations of Roman authority over other churches. In 189, assertion of the primacy of the Church of Rome may be indicated in Irenaeus's Against Heresies: "With [the Church of Rome], because of its superior origin, all the churches must agree ... and it is in her that the faithful everywhere have maintained the apostolic tradition." In 195 CE, Pope Victor I, in what is seen as an exercise of Roman authority over other churches, excommunicated the Quartodecimans for observing Easter on the 14th of Nisan, the date of the Jewish Passover. Celebration of Easter on a Sunday, as insisted on by the pope, is the system that has prevailed.

When Constantine became emperor of the Western Roman Empire in 312, he attributed his victory to the Christian God. Many soldiers in his army were Christians, and his army was his base of power. With Licinius (Eastern Roman emperor), he issued the Edict of Milan, which mandated toleration of all religions in the empire. Decisions made at the Council of Nicea (325) about the divinity of Christ led to a schism; the new religion, Arianism, flourished outside the Roman Empire. Partially to distinguish themselves from Arians, Catholic devotion to Mary became more prominent. This led to further schisms. 

In 380, the Edict of Thessalonica declared Nicene Christianity, as opposed to Arianism, to be the state religion of the empire, with the name "Catholic Christians" reserved for those who accepted that faith. While the civil power in the Eastern Roman Empire controlled the church, and the Ecumenical Patriarch of Constantinople, the capital, wielded much power, in the Western Roman Empire the Bishops of Rome were able to consolidate the influence and power they already possessed. After the fall of the Western Roman Empire, barbarian tribes were converted to Arian Christianity or Catholicism; Clovis I, king of the Franks, was the first important barbarian ruler to convert to Catholicism rather than Arianism, allying himself with the papacy. Other tribes, such as the Visigoths, later abandoned Arianism in favor of Catholicism.

The Middle Ages

After the fall of the Western Roman Empire, the pope served as a source of authority and continuity. Pope Gregory I (c. 540–604) administered the church with strict reform. Gregory was from an ancient senatorial family, and worked with the stern judgement and discipline typical of ancient Roman rule. Theologically, he represents the shift from the classical to the medieval outlook; his popular writings are full of dramatic miracles, potent relics, demons, angels, ghosts, and the approaching end of the world.

Gregory the Great

Pope Gregory I (c. 540–604) who established medieval themes in the church, in a painting by Carlo Saraceni, c. 1610, Rome.

The Byzantine Papacy was a period of Byzantine domination of the papacy from 537 to 752, when popes required the approval of the Byzantine Emperor for episcopal consecration, and many popes were chosen from the apocrisiarii (liaisons from the pope to the emperor) or the inhabitants of Byzantine Greece, Byzantine Syria, or Byzantine Sicily. Justinian I conquered the Italian peninsula in the Gothic War (535–554) and appointed the next three popes, a practice that would be continued by his successors and later be delegated to the Exarchate of Ravenna. With the exception of Pope Martin I, no pope during this period questioned the authority of the Byzantine monarch to confirm the election of the bishop of Rome before consecration could occur. 

From the late-6th to the late-8th century there was a turning of the papacy to the West and an escape from subordination to the authority of the Byzantine emperors of Constantinople. This phase has sometimes incorrectly been credited to Pope Gregory I (who reigned from 590 to 604 CE), who, like his predecessors, represented to the people of the Roman world a church that was still identified with the empire. Unlike some of those predecessors, Gregory was compelled to face the collapse of imperial authority in northern Italy. As the leading civil official of the empire in Rome, he was compelled to take over the civil administration of the cities and negotiate for the protection of Rome itself with the Lombard invaders threatening it. Another part of this phase occurred in the 8th century, after the rise of the new religion of Islam had weakened the Byzantine Empire and the Lombards had renewed their pressure in Italy. The popes finally sought support from the Frankish rulers of the West and received from the Frankish king Pepin The Short the first part of the Italian territories later known as the Papal States. With Pope Leo III's coronation of Charlemagne, first of the Carolingian emperors, the papacy also gained the emperor's protection; this action established the precedent that, in Western Europe, no man would be emperor without being crowned by a pope.

Second Phase of Papal Supremacy

The second great phase in the process of papal supremacy's rise to prominence extended from the mid-11th to the mid-13th century. It was distinguished, first, by Gregory VII's bold attack after 1075 on the traditional practices whereby the emperor had controlled appointments to the higher church offices. This attack spawned the protracted civil and ecclesiastical strife in Germany and Italy known as the Investiture Controversy. At issue was who, the pope or the monarchs, had the authority to appoint (invest) local church officials such as bishops of cities and abbots of monasteries. The conflict ended in 1122, when Emperor Henry V and Pope Calixtus II agreed on the Concordat of Worms, which differentiated between the royal and spiritual powers and gave the emperors a limited role in selecting bishops. The outcome seemed mostly a victory for the pope and his claim that he was God's chief representative in the world. However, the emperor did retain considerable power over the Church.

Papal supremacy was also increased by Urban II's launching in 1095 of the Crusades, which, in an attempt to liberate the Holy Land from Muslim domination, marshaled under papal leadership the aggressive energies of the European nobility. Both these efforts, although ultimately unsuccessful, greatly enhanced papal prestige in the 12th and 13th centuries. Such powerful popes as Alexander III (r. 1159–81), Innocent III (r. 1198–1216), Gregory IX (r. 1227–41), and Innocent IV (r. 1243–54) wielded a primacy over the church that attempted to vindicate a jurisdictional supremacy over emperors and kings in temporal and spiritual affairs. Throughout the rest of the Middle Ages, popes struggled with monarchs over power.