The Christianization of Europe was initiated by missionaries from the early Christian centres of Constantinople, Ephesus and Rome. It proceeded along the routes laid out by the former Roman Empire, using its infrastructure and administration. The Roman Empire had lost its power, since Italy was overrun by the Germanic tribes of the Goths during the Great Migration (3rd to 6th century). But Roman structures were still in place in the former provinces. The so-called “Gallo-Roman belt” west of the Rhine and south of the Danube, including the whole of France, western England, Ireland and Scotland were swiftly christianised. Trier and Cologne – in todays’ Germany – were the northernmost urban strongholds of Christianity. They were among the earliest bishoprics in the world, almost as old as the Bishopric of Rome itself.
The Germanic tribe of the Franconians (Franks) had turned out to be the most successful one throughout the centuries of the Great Migration. They kept on expanding from their tiny land of origin at the Rhine delta and conquered most of today’s France, Burgundy and western Germany. The king of the Franks, Chlodwig or Clovis, was married to Chrodechildis, a Catholic princess from Burgundy, who naturally influenced him to perceive his victories as a sign of the Christian God. In the year 498 he had himself baptised by the Bishop Remigius of Reims. 3000 men followed his example. Through his deed of being baptised by an annunciate of the Catholic Church of Rome, Chlodwig gained legitimacy and, at the same time, strengthened the Roman Catholic pope by recognising him as the head of Christianity. – There were two Romes at that time, the western and Constantinople, competing to be the seat of Petrus’ successor. Chlodwig had made a decision for Europe and the world: Frankish Empire would be Roman Catholic.
However, the progress of the new faith in the larger part of Germany, east of the Rhine and north of the Danube, in Hesse, Thuringia, Saxonia, Bavaria and especially in northern Germany, was very different. These areas had been briefly and superficially christianised by Iro-Scottish monks, and a few individuals had founded monasteries. The life style and way of thinking was still pagan, superstitious and fearful. The mission took this into account by incorporating old Germanic traditions, for example celebrated Christmas exactly at the date of the winter soltice, adorned church doors with grimaces to keep evil spirits out and created a cult of relics, which rendered something tangible to the worship of an invisible god.
Probably in the year 723 falls the most famous deed of Boniface, the English Father of German Christianity, when he felled the Donar-Oak near Geismar in Hesse. The tree was sacred, a place of worship for the heathen party in Hesse, which expected Donar, their god of war, to destroy the Christian attacker immediately. When this did not happen, many converted to the new creed, and Boniface built a church from the wood of the oaktree, and a monastery to deepen the understanding of the new religion.
In these areas the monasteries were the main centres of social and religious and – last, but not least – economic life. They fulfilled the functions of hospitals, hotels, and charity by feeding the poor. Nevertheless, the period from the 6th to the 10th century can rightfully be called the Dark Age, because only clergymen were allowed to read, and the only permitted book was the Bible. With education reduced to theology and even that forbidden to all but the clergy, the result was a society sunk in illiteracy for almost 1000 years.
In the 8th century, Charlemagne (Carl the Great or “Karl der Grosse” in German), had the vision of a united Christian world empire. He gave the church a hierarchy, founded schools for clerics, conquered Lombardy and Bavaria and set out on a 30 year long war against the persistently pagan Saxons in the north of Germany. This type of mission didn’t rely on conviction or persuasion, but used the sword extensively. Masses of people were forcefully baptised. One day in 782 the Franks decapitated 4500 Saxons in the town of Verden. When Duke Widukind of the Saxons was forced to convert in the year 785, Saxony was incorporated into the Frankish Empire. In 800, Charlemagne was crowned Emperor by the Roman Catholic Pope. When he died, his empire reached from the south of Italy and the north of Spain up to Danmark, from France to the plains of Hungary. It was the last common empire, before France and Germany split up into separate states.