Christian influences in Islam could be traced back to the Eastern Christianity, which surrounded the origins of Islam. Islam, emerging in the context of the Middle East that was largely Christian, 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, a Syriac scholar. The majority of Muslim countries also use a Gregorian calendar and some countries observe Sunday as a non-working day (cf. Sunday Sabbatarianism).