Bar Sauma was a teacher at the School of Edessa in the 5th century, but had to flee to Persia because of his Nestorian views. The teaching of Nestorius had been condemned in Ephesus in 431. Nestorius was a student of Theodore of Mopsuestia, who was held in very high esteem by the Assyrian Church, and so Nestorius was received well. Even the Persian kings, who were Zoroastrian and at constant war with the Byzantine Empire, favored him.

He became bishop of Nisibis and later Catholicos of the Assyrian Church of the East. As such he headed the Synod of Beth Lapat in (484) where the teaching of Nestorius became the official doctrine, and the Assyrian Church broke with the Byzantine Church. At this synod it was also decided that all monks and church dignitaries should marry, apparently to please the Zoroastrian rules, which held family life sacred.

The decisions of Beth Lapat didn't win the church much favor with the authorities, and weakend its spiritual life. Some of the decisions were already reverted at the episcopal gathering of 544.

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