Christian influences on the Islamic world
Christian influences in Islam can be traced back to Eastern Christianity, which surrounded the origins of Islam. Islam, emerging in the context of a largely Christian Middle East, was first seen as a Christological heresy known as the "heresy of the Ishmaelites", described as such in Concerning Heresy by Saint John of Damascus.
Source: Wikipedia — Christian influences on the Islamic world (CC BY-SA 4.0)