Pulcheria used her wealth for the [[church]]. In doing this she inspired her brother to do likewise. While she appeared to be indifferent to [[Arianism]] that was practiced by the German tribes, she took a firm position on the heretical teaching of [[Nestorius]]. She almost immediately became antagonistic against him when he became [[Patriarch]] in 428. Whether the downgrading of the status of the Virgin Mary from Theotokos to Christotokos under Nestorianism was involved, Pulcheria greatly influenced her brother’s position in the controversies that led up to the [[Third Ecumenical Council|Council in Ephesus]] in 431. He, at first, was a supporter of Nestorius before acceding to his sister’s position. In this controversy Patr. [[Cyril of Alexandria]] believed Pulcheria’s influence was important in the downfall of his rival.
In 441, Pulcheria’s influence on her brother began to wain as the eunuch Chrysaphius convinced Theodosius to dismiss his sister. But, soon the [[Monophysitism|Monophysite]] controversy was raised by the [[archimandrite]] Eutyches and supported by Theodosius as well as by Cyril’s successor as [[Patriarchs of Alexandria|Patriarch of Alexandria]], Dioscorus. When Eutyches’ views were validated at the ‘Robber Council’ of 449 in Ephesus, Pope Leo I of Rome included Pulcheria among those he approached for help in reversing the decisions of the council.
On [[July 26]], 450, Theodosius suddenly died, and Pulcheria returned to the court as the wife of the new emperor, Marcian. She had agreed in the marriage with the understanding that her vow of chastity would be honored. In 451, the [[Fourth Ecumenical Council|Council of Chalcedon]], presided over by Marcian, was convened that condemned Nestorianism as well as the [[Robber Council of 449]] that had supported the Monophysite [[heresy]]. The [[heretic]] Eutyches was deposed and exiled.