Nestorius, the fifth-century patriarch of Constantinople who was condemned as a heretic by the council of Ephesus in 431. among the Assyrian beliefs that Rubruck held to be heretical was that the virgin Mary was the mother of Christ, but not the mother of god. They also differed from Catholics in their steadfast refusal to portray Christ on the cross as a violation of the Mongol taboos on depicting death or blood.