Great schools of theology and philosophy also flourished within this great church, and it is well known fact that Arabian philosophy, mathematics, medicine, the arts and science of the Middle Ages, though to a great extent of Greek origin, penetrated the Abbaside Empire through the influence of the numerous Nestorian and Jacobite scholars and schools of learning; and thus preserved Western culture from utter destruction and made possible its reintroduction into Europe through Spain at the hands of the Mohammedan Arabs.

  Up to about the middle of the 5th Christian century, the Assyro-Chaldean Christians professed the same Orthodox Christian Faith. In 429, Nestorius, a native of Syria and Patriarch of Constantinople, began to preach his doctrine that in Christ there were two distinct persons (the human and the divine) just as there were in Him two distinct corresponding natures, and thus denying the Divine Maternity of the Virgin Mary, condemned by the Council of Ephesus (431) and repudiated by the whole Church of the West, and finding no outlet for his doctrine in the Roman Empire, Nestorius, or rather his Syrian followers and admirers, bishops, priests and monks, found in Mesopotamia and Persia a fertile field for their teaching. Aided by the Sassanian kings of Persia, the inveterate enemies of the Roman Empire and of the Western Christianity, they succeeded in propagating Nestorianism throughout the length and breadth of the Persian Empire, with the result that within a few decades the vast and powerful Christian Church of Persia embraced the Nestorian doctrine and thus separated itself from the Christianity of the West, becoming an autonomous church.