Complex sentence: Later, during the Synod of Diamper these churches were reconsecrated either to all saints or to St. Gervase or Portase, based on the Roman catholic Portuguese presumption that these two Syrian bishops and all Syrian churches were heretic.
Split into simpler sentences: Later, during the Synod of Diamper these churches were reconsecrated either to all saints or to Sts. Gervase and Portase, based on the Roman catholic Portuguese presumption that these two Syrian bishops and all Syrian churches were heretic.