The writings of the Venerable Bede (written around 700AD in a monastery in Jarrow in Northumberland founded by the St Patrick movement) are a testimonial to this.(e.g. his “Ecclesiastical History of the English People”).
Three other major events took place in Europe to fully establish the Christian Church across Europe.
The Roman Byzantium Empire centred in Constantinople was not over run by the Germanic tribes as befell Rome
Pope Leo 3rd in about 800 came to a deal with the effective Emperor of Europe, Charlemagne, and crowned him Emperor of the Western Church or Holy Roman Emperor. (Charlemagne was of German stock whose court was in Aachen/Aix-la-Chapelle in the west of Germany.) On Charlemagne’s death the crown passed to the German Kings. The best remembered of course being the Habsburgs whose court was in Vienna Austria and then perhaps Charles 5th from Burgundy now in France who also became king of Spain and Naples in Italy The succession of the Holy Roman Empire remained solid until 1800 when it collapsed under Napoleon.
Perhaps the most holy, respected and useful activities of the Christian church were their monasteries which were centres for dedicated religious people to live, work and pray, generally eight times a day. They became the best brains of their day and most importantly did good works in their neighbourhood. This took the form of creating books for reading before printing was invented, teaching, the only real source of education at the time, and such things as helping local farmers with capital projects they could not afford like draining the land. The men and women who lived in monasteries took vows to spend their lives doing good works in the name of God. Marriage was disallowed for monks and nuns. The first simple monasteries were set up in Ireland by St Patrick where one of their key jobs was to make copies, by hand of course, of all the vital Christian books being rapidly destroyed by the Saxons and Vikings in England.