Christianity as the Roman state religion in the context of "Cultural amalgamation"

The History of the Decline and Fall of the Roman Empire, sometimes shortened to Decline and Fall of the Roman Empire, is a six-volume work by the English historian Edward Gibbon. The six volumes cover, from 98 to 1590, the peak of the Roman Empire, the history of early Christianity and its emergence as the Roman state religion, the Fall of the Western Roman Empire, the rise of Genghis Khan and Tamerlane and the fall of Byzantium, as well as discussions on the ruins of Ancient Rome.

Volume I was first published in February 1776 by William Strahan and Thomas Cadell. It was reissued in a succession of six revised editions between 1776 and 1789. Volumes II and III appeared in 1781, and the final three volumes (IV–VI) were issued together in 1788. All six volumes of the first edition were published in quarto; later octavo reprints followed from 1783 onward.

Early Christians were heavily persecuted throughout the Roman Empire until the 3rd century. Although Christianity initially emerged as a small Jewish movement in 1st-century Judaea, it quickly branched off as a separate religion and began spreading across the various Roman territories at a pace that put it at odds with the well-established Roman imperial cult, to which it stood in opposition; Christians were vocal in their expressions of abhorrence towards the beliefs and practices of Roman paganism, such as deifying and making ritual sacrifices to the Roman emperor or partaking in other methods of idolatry. Consequently, the Roman state and other members of civic society routinely punished Christians for treason, various rumoured crimes, illegal assembly, and for introducing an alien cult that drove many Roman people to apostasy in favour of Jesus Christ. According to Tacitus, the first wave of organized persecution occurred under Nero (r. 54–68), who blamed Christians for the Great Fire of Rome in 64. A number of mostly localized persecutions occurred during the reign of Marcus Aurelius (r. 161–180). After a lull, persecution resumed under Decius (r. 249–251) and Trebonianus Gallus (r. 251–253). The Decian persecution was particularly extensive, as Decius strived to restore the Roman golden age in part by forcing pagan practices upon the Christian community. Another wave of persecution began under Valerian (r. 253–260), but ceased abruptly after he was captured and taken prisoner by the Sasanian Empire during the Battle of Edessa of the Roman–Persian Wars. Under his successor Gallienus (r. 253–268), whose reign was marred by rapidly escalating military conflicts of the Crisis of the Third Century, the first ever decree of tolerance was issued for Christian practices and places of worship, although it stopped short of recognizing Christianity as a religion with legal status.

Emperor Diocletian (r. 283–305) began the Diocletianic persecution, which was the final and the most severe wave of persecution of Christians by the Roman state. It was enforced until the accession of Galerius (r. 305–311), who issued the Edict of Serdica, and the death of Maximinus Daza (r. 310–313). After Constantine the Great (r. 306–337) defeated his rival Maxentius (r. 306–312) at the Battle of the Milvian Bridge in October 312, he and his co-emperor Licinius issued the Edict of Milan, which decriminalized Christianity and suppressed pagan populations throughout the Roman Empire. In 380, Theodosius I (r. 379–395) issued the Edict of Thessalonica, officially establishing Christianity as the Roman state religion. It was also during the reign of Theodosius I that pagan practices were overtly deemed punishable offenses, which laid the framework for early Byzantine anti-pagan policies.

Basil of Caesarea, also called Saint Basil the Great (330 – 1 or 2 January 379) was an early Roman Christian prelate who served as Bishop of Caesarea in Cappadocia from 370 until his death in 379. He was an influential theologian who supported the Nicene Creed and opposed heresies within the early Christian church such as Arianism and Apollinarianism.

In addition to his work as a theologian, Basil was known for his care of the poor and underprivileged. Basil established guidelines for monastic life which focus on community life, liturgical prayer, and manual labor. Together with Pachomius, he is remembered as a father of communal monasticism in Eastern Christianity. He is considered a saint by the traditions of both Eastern and Western Christianity.

The Carolingian Renaissance was the first of three medieval renaissances, a period of cultural activity in the Carolingian Empire. Charlemagne's reign led to an intellectual revival beginning in the 8th century and continuing throughout the 9th century, taking inspiration from ancient Roman and Greek culture and the Christian Roman Empire of the 4th century. The period saw an increase of literature, writing, visual arts, architecture, music, jurisprudence, liturgical reforms, and scriptural studies. Carolingian schools were effective centers of education, and they served generations of scholars by producing editions and copies of the classics, both Christian and pagan.

The movement occurred mostly during the reigns of Carolingian rulers Charlemagne and Louis the Pious. It was supported by the scholars of the court, notably Alcuin of York. Charlemagne's Admonitio generalis (789) and Epistola de litteris colendis served as manifestos. Alcuin wrote on subjects ranging from grammar and biblical exegesis to arithmetic and astronomy. He also collected rare books, which formed the nucleus of the library at York Cathedral. His enthusiasm for learning made him an effective teacher. Alcuin writes:

The Byzantine Greeks, Byzantines or Eastern Romans (Greek: Ῥωμαῖοι, romanized: Rhōmaîoi) were the Greek-speaking people of the Byzantine Empire. They were Chalcedonian Christians who self-identified as Romans throughout Late Antiquity and the Middle Ages. Latin speakers identified them simply as Greeks or with the term Romaei. They were the main inhabitants of the capital Constantinople and lands of the Eastern Roman Empire, such as Asia Minor (modern Turkey), Cyprus, Greece, and portions in the rest of the southern Balkans and southern Italy; they also formed large minorities, or pluralities, in the coastal urban centres of the northern Black Sea coast, Levant, and northern Egypt.

Use of Greek was already widespread in the eastern Roman Empire when Constantine I (r. 306–337) moved its capital to Constantinople, while Anatolia had also been hellenized by early Byzantine times. The empire lost its predominantly non-Greek speaking provinces by the 7th century Muslim conquests and its population was overwhelmingly Greek-speaking by the 8th century. Unlike the early medieval West, the Greek education of the East was more advanced, resulting in widespread basic literacy. Success came easily to Greek-speaking merchants, who enjoyed a strong position in international trade.

Gregory of Nazianzus (Greek: Γρηγόριος ὁ Ναζιανζηνός, romanized: Grēgorios ho Nazianzēnos; c. 329 – 25 January 390), also known as Gregory the Theologian or Gregory Nazianzen, was an early Roman Christian theologian and prelate who served as Archbishop of Constantinople from 380 to 381. He is widely considered the most accomplished rhetorical stylist of the patristic age. As a classically trained orator and philosopher, he infused Hellenism into the early Church, establishing the paradigm of Byzantine theologians and church officials.

Gregory made a significant impact on the shape of Trinitarian theology among both Greek and Latin-speaking theologians, and he is remembered as the "Trinitarian Theologian". Much of his theological work continues to influence modern theologians, especially in regard to the relationship among the three Persons of the Trinity. Along with the brothers Basil of Caesarea and Gregory of Nyssa, he is known as one of the Cappadocian Fathers.

An encyclical was originally a circular letter sent to all the churches of a particular area in the ancient Roman Church. At that time, the word could be used for a letter sent out by any bishop. The word comes from the Late Latin encyclios (originally from the Latin encyclius, a Latinization of Greek ἐγκύκλιος (enkyklios), meaning "circular", "in a circle", or "all-round", also part of the origin of the word encyclopedia).

The term is now primarily associated with papal encyclicals from the Catholic Church for letters outlining the church's perspective on a topic, but is also used among Anglicans and the Eastern Orthodox Church.