SD67, I actually have read my history and have a couple of degrees in that field. There were no "conquering Christians" in Britain. The power of the Druids in western Europe and Britain was destroyed in a process begun during the time of the Roman Republic and finished while Christians were still being persecuted in the Colisseum. The Caesars destroyed the Druids.
The pagans of northern Europe, mainly of ancient germanic culture, were also either destroyed by the Romans or, as in the case of the Visigoths, conquered Rome itself. Many of these tribes migrated into the Empire seeking a haven from the ravages of the Huns. The wars between the Empire and these pagans has never been portrayed by historians as a "religious struggle."
The Byzantine Empire lived in relative peace with the peoples of the Middle East until the rise of militant Islam. The Byzantines were a bulwark against the intrusion of the muslims into Europe. After winning the Battle of Manzikert, the Turks closed the pilgrim roads to Palestine and repressed the Christian Armenians. The population of the Armenian capital of Ani was savagely massacred.
Four hundred years earlier, during the intial surge of militant Islam during the time of Muhammad, the Arabs had annihilated the Christian parts of Syria, Egypt, and North Africa, which had had a very prosperous past. The destruction of the great Christian basilicas in ALexandria, Hippo, Antioch, and Jerusalem date from this time of conquest.
The lot of the Christians who did not flee varied in different places and times; sometimes agreements between rulers such as Charlemagne and the Caliph Harun al-Rashid, made it easier and more pleasant. At other times these agreements were flouted in the cruellest and most deplorable way, as when the Caliph Hakim, at the beginning of the eleventh century for no apparent reason ordered the destruction of the Holy Sepulchre and began to harry and massacre Christians and Jews everywhere. (Source: The Crusades, by Regine Pernoud.)
By contrast, the "Christian conquest" of Europe was far more peaceful, if not perfectly so.
It was only after the Battle of Manzikert that the Byzantines, fearing the renewal of the Muslim onslaught, appealed to the Christian kingdoms of the west for aid. Revisionist history notwithstanding, the Crusades that resulted were not an unprovoked attack against a peaceful and enlightened Muslim society.
