Complex sentence: Vincent defended calling Mary, mother of Jesus, "Theotokos" ("God-bearer") which opposed the teachings of Patriarch Nestorius of Constantinople, which was condemned by the Council of Ephesus.
Split into simpler sentences: Vincent defended calling Mary, mother of Jesus, "Theotokos" ("God-bearer"). This opposed the teachings of Patriarch Nestorius of Constantinople and was condemned by the Council of Ephesus.