The Spread of Christianity (300 CE – 600 CE)
Witness the transformation of the Roman world. From Constantine's conversion to Gregory the Great, Christianity became the official religion of the empire, defined its doctrine through great councils, and began to shape the civilisation of Europe.
History: 300-600 CE
From Persecutionto Christendom
In 313, Constantine issued the Edict of Milan, granting Christians freedom of worship. Within decades, Christianity had become the favoured religion of the empire, and by 380, Theodosius made it the official state religion. The Church emerged from the catacombs to build basilicas and shape imperial policy.
The great ecumenical councils defined Christian doctrine. Nicaea (325) affirmed Christ's divinity against Arianism; Constantinople (381) completed the Nicene Creed; Ephesus (431) proclaimed Mary as Theotokos; Chalcedon (451) defined Christ's two natures. These councils established the orthodox faith that Catholics profess today.
As the Western Roman Empire collapsed, the Church became the guardian of civilisation. Monasteries preserved learning, bishops administered cities, and popes like Leo the Great negotiated with barbarian kings. By 600, Gregory the Great was sending missionaries to England and laying foundations for medieval Christendom.
At a Glance
313: The Edict of Milan
Constantine granted religious freedom, ending centuries of persecution and beginning the Christianisation of the empire.
The Great Councils
Nicaea, Constantinople, Ephesus, and Chalcedon defined the doctrines of Trinity and Incarnation.
The Fall of Rome
As the empire crumbled, the Church preserved learning and civilisation for future generations.
“In this sign, conquer.”
VO
Vision of Constantine
Before the Battle of Milvian Bridge, 312 CE
Building Christendom
These centuries laid the foundations of Christian Europe. The councils defined the faith, the monks preserved learning, and the popes became shepherds of nations.