Christian sources of mid seventh century give relatively little attention to Muslims and even less to Islam, but the number of references is still considerable. The Christian approach to early Islam and Muslim rule was mostly negative, or at best neutral, but in the early sources this was not because of the contents of Islamic belief but because of what the Islamic rule did to Christians. Insiders’ and outsiders’ perspectives on Islam and Muslims were constantly at odds, however, and should not be confused. When the Muslim rule was established and the society started to adapt the Islamic system, conversions started to take place on growing numbers. The first known cases are rather early and imply that a noteworthy number of conversions took place even in the pre-Umayyad era in some places. The dominating motive seems to have been the will to avoid the discriminating taxation. Had there been a considerable amount of conversions because of the belief in the Quranic revelation, theological authors would certainly have reacted heavily. It was only in Abbasid times, however, that a need for theological apologies appeared. Even if the early cases of conversion were somewhat random, they were nevertheless unprecedented. Apart from certain cases during the persecutions of the early Church, conversions away from Christianity in the Christian East had been almost non-existent. Therefore, the Islamic rule was perceived and interpreted as an apocalyptic disaster: Rome or Persia had not been able to conquer the Church by persecution, but for the first time in history, big numbers of Christians were denouncing their faith. This process intensified in latter half of the eighth century, but it was already on the rise a century earlier.
One of the theological challenges generated by the advent of Islam was that Christians had to reconsider their relation to Torah from a completely new angle. Consequently, Torah has an important place in the argumentation of Theodore Abū Qurrah, the first Orthodox Church father to write in Arabic, as well as in the earliest work of Islamic counter-polemics, surviving in the name of ʿAbd al-Jabbār. For both authors, the role of Torah was a central argument in defending the superiority of one’s own religion. Christians and Muslims did share the approach that Torah is to be read in the light of the religion that represents the highest form of truth, and both authors highlighted the features that were in line with his own religion. Theodore Abū Qurrah stressed the continuity of Christianity and Judaism, as well as miracles of Moses and Jesus in contrast to Muhammad’s separateness and lack of miracles. Correspondingly, ʿAbd al-Jabbār focused on the commandments of Torah that were common with the Qurʾan and Islam, like circumcision, prohibition of pork and ritual purity. With the help of these, he aimed to show that Christianity was thoroughly corrupted. As a curious side effect, both came to stress continuity and conformity with Judaism more than they admitted elsewhere. The rhetorical styles of the two authors differ somewhat, and both have their inconveniencies. Abu Qurrah operates in curious tension. On the one hand, he tries to adjust himself to the Islamic patterns of thought and expression, which makes it somewhat difficult for him to express the fundamental ideas and attitudes of the Christian tradition; and on the other hand, at times he gives traditional Byzantine answers that do not really match with the Islamic questioning. ʿAbd al-Jabbār’s approach is characterised by extreme selectiveness, even by standards of polemical literature. His view on the history of early Christianity is not only an imbalanced construction but a determined distortion of the first Christian centuries.