Pagan - Christianity........
British
British were pagans before the arrival of the Romans. They had a system of religious veneration i.e, human head. It was considered pious indulging human sacrifice.
Roman invasion exterminated a group of wise men among them known as the Druids. They were considered as a threat to the Romans inciting the natives to rebellions.
Officially in the 4th century AD, Christianity became the main community of the Roman Empire. Many of them converted to Christianity before this date. For instance Alban, who was a 3rd century British Christian, was put to death at Verulamium. After that he became Saint Alban (the modern town Verulamium is named after him. The ruins of were still there)
The Romans worshipped many gods and goddesses. They identified the local gods wherever they went to invade and combined them with their own sanctity. For instance, at Aqua Sulis (Bath), the goddess of the hot springs called Sulis was combined with the Roman goddess of wisdom called Minerva to become Sulis Minerva. In Bath, still we find the head of the great statue of Sulis Minerva.
Britain was invaded by Pagan Saxons, after the fall of the Romans. Eventually they were converted to Christianity by missionaries from Rome.
The Pagan World
History illustrated that the world was reigned by dark nights of egoism and cruelty before Lord Jesus Christ preached the Good News of the Gospel among men.The picture referred that all Romans, Greeks, and "barbarians" were not dissoluted. Minorities were at variance with that situation, however they were prepared for the evangelical preaching. This lead to the rapid expansion of the Catholic Church and, finally the Empire converted into a Christian era.
[... The Pagan] Gods developed a violent band of miscreants. They were oppressors and murderers involving in patricide, matricide and fratricide. Instances of these evil doings were retold in texts instructing children in grammar, rhetoric, and poetry in the schools of that era, as pointed out by Christian apologists.