What was the Roman empires of use of Christianity at various points and its history? What caused him to change over time?

The Roman Empire's use of Christianity evolved over time, as the empire went through various stages and emperors with different priorities. Initially, Christianity faced persecution in the Roman Empire, but eventually, it became the official religion and enjoyed imperial patronage. Here is a brief overview of the Roman Empire's relationship with Christianity and the factors that influenced its changes over time:

1. Early Persecution (1st to 3rd Century AD):
During the first few centuries AD, the Roman Empire viewed Christianity as a threat to its political stability and religious unity. Christians were seen as deviant and refusing to worship the Roman gods, which were an essential part of the empire's religious and civic rituals. Consequently, they faced sporadic periods of persecution, including martyrdom under emperors like Nero and Diocletian.

2. Constantine and Legalization (4th Century AD):
In the early 4th century, Emperor Constantine experienced a significant shift in his religious policy. According to tradition, Constantine witnessed an apparition before a decisive battle, and he attributed his victory to the Christian God. As a result, he issued the Edict of Milan in 313 AD, legalizing Christianity and bringing an end to the persecution. This marked the first major change in the Roman Empire's relationship with Christianity.

3. Official Religion (4th Century AD):
Over time, Christianity gained prominence within the empire, and its influence grew. In 380 AD, Emperor Theodosius I issued the Edict of Thessalonica, which declared Christianity as the sole legal religion of the Roman Empire. This marked the point when Christianity became the official state religion and received considerable imperial support.

4. Rise of Church Influence:
As Christianity became the state religion, the Church started to play a more significant role in both religious and political affairs. Bishops gained considerable authority and began exerting influence on imperial policies. This growing influence could be seen in matters such as ecclesiastical disputes, theological debates, and the eventual division of the Roman Empire into Western and Eastern halves.

5. Barbarian Invasions (5th Century AD):
Towards the end of the 4th century, the Roman Empire faced numerous challenges, including barbarian invasions and internal political instability. As the empire struggled to maintain its control, Christianity played a unifying role through its ability to transcend ethnic and cultural boundaries. It offered an underlying principle of unity, acting as a binding force, especially within the fragmented Western Roman Empire.

It is important to note that throughout this period, individual emperors had varying degrees of personal piety and interest in Christianity, which further influenced the empire's relationship with the religion. Additionally, as Christianity grew in prominence and influence, debates, theological controversies, and power struggles within the Church itself also impacted its dynamics with the empire.

The Roman Empire's use of Christianity evolved throughout its history. Here, I will provide a step-by-step overview of the Roman Empire's relationship with Christianity and the factors that influenced this relationship:

1. Early Persecution (30-313 AD): In the early years, the Roman Empire viewed Christianity as a threat to its religious and political stability. This led to sporadic persecutions of Christians, including the crucifixion of Jesus and the martyrdom of many early believers.

2. Constantine's Conversion (312 AD): Emperor Constantine played a crucial role in Christianity's history within the Roman Empire. In 312 AD, he claimed to have a divine vision; he saw a symbol called the Chi-Rho (☧) and heard the phrase "In this sign, conquer." After his victory at the Battle of Milvian Bridge, Constantine issued the Edict of Milan in 313 AD, granting religious tolerance to Christians.

3. Edict of Thessalonica (380 AD): The Roman Empire continued to embrace Christianity under Emperor Theodosius I. In 380 AD, he issued the Edict of Thessalonica, making Nicene Christianity the official state religion. This further solidified Christianity's role and influence within the empire.

4. Split of the Empire (395 AD): Following the death of Theodosius I, the Roman Empire split into the Western and Eastern Roman Empires. The Western Empire faced numerous external invasions, which contributed to its eventual collapse. Christianity remained the dominant religion in both empires, but political instability affected the church's role.

5. Barbarian Invasions and Conversion (4th-6th century): As barbarian tribes invaded the Western Roman Empire, many of them adopted Christianity. The conversion of these tribes played a role in preserving Christian institutions and spreading the faith throughout Europe.

6. Byzantine Empire (476-1453): The Eastern Roman Empire, also known as the Byzantine Empire, continued as a unified Christian state throughout its existence. Although it faced internal conflicts, religious controversy, and power struggles with the Roman Catholic Church, Christianity remained deeply intertwined with Byzantium's identity and governance.

7. The Great Schism (1054 AD): The Great Schism marked the official split between the Roman Catholic Church and the Eastern Orthodox Church. This further divided Christianity within the Byzantine Empire and strained its relationship with the Western Roman Catholic Church.

8. Fall of Constantinople (1453 AD): The fall of Constantinople to the Ottoman Empire in 1453 led to the end of the Byzantine Empire. As a result, Christianity faced significant challenges and had to adapt to the changing political landscape.

Factors that caused the Roman Empire's changing relationship with Christianity over time include:
- The conversion of Emperor Constantine and subsequent state sponsorship
- Barbarian invasions and the spread of Christianity among the invaders
- Political instability within the empire
- The split between the Eastern and Western Roman Empires
- Internal religious conflicts, like the Great Schism
- External threats to the empire, such as the Ottoman conquest of Constantinople