Haeresiarch

Nestorǐus, a celebrated Haeresiarch, was appointed patriarch of Constantinople a.d. 428, but in consequence of his heresy was deposed at the council of Ephesus, 431. […] Nestorius carefully distinguished between the divine and human nature attributed to Christ, and refused to give to the Virgin Mary the title of Theotocus (Θεοτόκος) or "Mother of God."