Constantine and the Council of Nicea

As described on the page Early Church persecutions, for the first three centuries the Christian church suffered immense persecution from the Roman authorities and elsewhere. This had the advantage of spreading the Christian message widely. Believers fled for their lives to the furthest frontiers of the known world. That changed after the Edict of Milan and the Council of Nicea.

The Edict of Toleration

Christianity was first de-criminalised by the Edict of Toleration. The Emperor Galerius signed it in 311 on his deathbed. He declared that all religions should be tolerated. Galerius shared the role of Emperor with Constantine from the year 306. After Galerius died, Constantine and Licinius shared the rule of the Roman Empire.

In 312 Constantine, whose parents may have had Christian leanings, was about to take part in a battle. Legend has it that he saw a vision with a Christian symbol, and Latin words meaning ‘In this sign conquer’. He won the battle, and took his vision as a divine calling to favour Christians. It is unlikely that he himself became a Christian believer at the time. He retained the title of High Priest of the traditional Roman pagan religion, and had members of his family killed when he perceived them as threats. He was not baptised until he was dying.

The Edict of Milan

Nonetheless, Christians had a much easier time under the rule of the Emperor Constantine. He and Licinius passed the Edict of Milan in 313, which officially gave Christians freedom to worship as they wished. Constantine also passed edicts restoring property to churches, removed under previous antagonistic Emperors. He ordered and paid for fifty hand-lettered copies of the Bible to be made. This was quite an undertaking in centuries before the printing press was invented!  He then sent it to important congregations around the Empire.

Constantine also subsidised the church financially. He declared that Sundays should be official state holidays for rest and worship. He built a new city – Constantinople – where he ordered new churches to be built. This was the beginning of the ecclesiastical structures and increased formality in services. The new, ‘official’ Christianity appealed to the wealthy and upper classes, who were more likely to move in formal court circles.

The Council of Nicea

Ordinary Christians found life much easier under Constantine. However, peace and tolerance led to further divisions and heresies among some of the church leaders. You can read about some or the earlier ones on the page Early Church heresies. Another one that became more prominent during the fourth century was known as the Arian heresy. Arius, who first proposed it, was a popular preacher who denied the deity of Jesus Christ. He was trying to ensure that Christians did not believe in multiple gods, as the Romans did. But in doing so he denied the Trinity. He declared that Jesus was not God but a divinely created being.

Heresies were generally resolved by meetings of church leaders, or bishops, at councils; the Arian heresy was first on the agenda at the Council of Nicea (in Turkey) in the year 325, where three hundred bishops convened to agree matters of doctrine. Alexander, the bishop of Alexandria (in Egypt) declared that the Scriptures and the teaching of the Apostles was that Jesus should be considered co-equal with God the Father, and worshipped as God. Arius denied this.

Constantine demanded that the bishops have a vote to determine the majority view, and that they should develop a creed – or statement of belief – which could be said and believed by all Christians. One of the most vocal speakers on the view of Jesus’ divinity was Athanasius, one of Alexander’s students, who was to become his successor. The bishops voted to affirm Alexander’s views, that Jesus is indeed God, and the Nicene Creed was written, something that is still sometimes used today by Christians of all denominations and confessions.

Early monasteries

There were some Christians who felt that persecution enabled them to suffer for God, and that the widespread acceptance of Christianity made life too easy for them; an increased number decided to enter the monastic life. At first monks lived on their own, but around this time started joining in groups to share resources. So monasteries began, perhaps with Pachomius.


Other Christians broke away from the majority, insisting that they were the only ‘true’ church. Some of them insisted that ministers who fell away from the faith during persecution no longer had any authority, and that baptism and Communion administered by these ministers was invalid. One of the leaders of one of this group was Donatus, and his followers were known as Donatists. They grew quite strong in some remote areas, even taking up arms sometimes to defend their beliefs.

Church Fathers

Despite the Council of Nicea, many Christians continued debating the fine points of Christian doctrine, and raising further questions and problems. This led to some extensive writing about Christian doctrine and history, from men whom we now call the ‘Church Fathers’.

Eusebius of Caesarea (c 263-340) was a gentle, scholarly man who wrote ‘Ecclesiastical History’. This was about the church from the time of the Apostles until the Council of Nicea. He is sometimes called the father of church history.

Athanasius (c 293-373) and his followers wrote several theological works, clarifying the doctrine of the Trinity – Father, Son and Holy Spirit. A later council officially adopted this as Christian doctrine in the year 381: the Council of Constantinople.

Ambrose (c 340-397) became Bishop of Milan in 374. He was educated as a lawyer, and was a good administrator and speaker. He encouraged hymn and psalm singing in his congregation.

John Chrysostom (347-407) was a well-known preacher of the time, who attacked injustice. He wrote some of the first Bible commentaries, and in 397 became Bishop of Constantinople. However he was banished due to his outspoken preaching against sin and immorality. He eventually died in exile.

Jerome (c 347-420) was classically educated in Italy, and became a monk in Palestine. He is best known for his scholarly translation of the Bible into Latin. Before attempting this he learned Hebrew from Jewish rabbis, and perfected his Greek. His translation is known as the Vulgate and was used in Latin-speaking churches right through the Middle Ages.

Theodore of Mopsuestia (c350-428) became a bishop in 392. He stressed the importance of believing in a literal interpretation of the Bible. He also stressed that people should understand it all in its context.

Augustine of Hippo (354-430) grew up in North Africa. He first adopted the Manichaean heresy, then rejected that in favour of neo-Platonic rhetoric. Eventually he converted to Christianity in 386 after reading part of the book of Romans. He was baptised in Milan where he became a bishop. He then wrote against his prior beliefs, and against Donatism, and Pelagianism which stressed the human role in salvation. Augustine developed a doctrine of the church and the theory of justification by grace, and predestination. He also wrote his ‘Confessions’, recounting his wild youth, and the story of how God led him.

More church history pages:

Church history begins
Paul’s Missionary Journeys
Early church persecutions
Christian martyrs in the third century
Early church heresies