Pre-Islamic
At the age of nine, Muhammad went to Syria with his uncle and had interactions with Christians. One important contact was with the Nestorian monk Bahira in Bosra, modern Syria who foretold to the adolescent Muhammad his future prophetic career.
Waraqah ibn Nawfal was a Nestorian monk, Mecca's priest or preacher according to some sources.
Read more about this topic: Muhammad's Views On Christians