Pope titleHe first introduced the title of "Pope" as the head of the Church. It was later made the official title by Pope Boniface III (607).
Third Eumenical CouncilHe excommunicated Nestorius, the Bishop of Constantinople, and his followers as heretics.
Mary worshipWorship of Mary is adopted.
395-423: Western Roman Emperor, Flavius Honorius
408-450: Eastern Roman Emperor, Theodosius II
425-455: Western Roman Emperor, Valentinian III
429-534: Vandal Empire established in North Africa
431: Council of Ephesus proclaims that Mary is Theotokos (Mother of God)
Mary worship is made an official church doctrine
431: Crosses in churches introduced