“Christendom” has referred to the notion of the Christian world as a sociopolitical polity. In essence, the earliest vision of Christendom was a vision of a Christian theocracy, a government founded upon and upholding Christian values, whose institutions are spread through and over with Christian doctrine. In this period, members of the Christian clergy wield political authority. The specific relationship between the political leaders and the clergy varied but, in theory, the national and political divisions were at times subsumed under the leadership of the church as an institution. This would tempt Church leaders and political leaders alike throughout the time in European history.
Depiction of Constantine and the Nicene Fathers holding the Nicene Creed.Emperor Constantine issued the Edict of Milan in 313 proclaiming toleration for the Christian religion, and convoked the First Council of Nicaea in 325 whose Nicene Creed included belief in “one holy catholic and apostolic Church”. Christianity became the state religion of the Empire in 392 when Theodosius I prohibited the practice of pagan religions. The Church gradually became a defining institution of the Empire.
The accession of Constantine was a turning point for the Christian Church, generally considered the beginning of Christendom. After his victory, Constantine took over the role of the patron for the Christian faith. He supported the Church financially, had an extraordinary number of basilicas built, granted privileges (e.g. exemption from certain taxes) to clergy, promoted Christians to high ranking offices, and returned property confiscated during the Great Persecution of Diocletian, and endowed the church with land and other wealth. Between 324 and 330, Constantine built, virtually from scratch, a new imperial capital at Byzantium on the Bosphorus (it came to be named for him: Constantinople) – the city employed overtly Christian architecture, contained churches within the city walls (unlike “old” Rome), and had no pagan temples.
One of the greatest seismic events recorded in Church history occurred in the farthest west corners of Asia. It influenced Christianity—Orthodox Christianity in particular–everywhere for all the centuries to follow. The epicenter was Byzantium and begins with the Roman Emperor Constantine (285-337 A.D.) entering the scene and shaping the course of the development of Christianity.
According to the Church historian Eusebius, Constantine received a vision from heaven. Before the major battle at the Milvian Bridge outside of Rome in 312 against Maxentius (278-312), a rival for the throne, he looked into the sky heard a voice, and in the vision saw the symbol, “ΧΡ” (Chi-Rho), the first two Greek letters of the title of Christ. The word he heard with it said: “In this sign, conquer.”
Since the emperor did conquer, Constantine credited it as the sign of God’s favor for victory. Until then emperors persecuted or, at least tolerated Christianity. Now the tide changed with Constantine’s conversion. As the victory-bringing sign, the emblem of Christ the Savior became the ecumenical (worldwide) insignia of Christendom.
