and Son are similar but not identical in substance, could not explain how Jesus could accomplish the redemption of humankind which is the foundational principle of Christianity. "According to Athanasius, God had to become human so that humans could become divine ... That led him to conclude that the divine nature in Jesus was identical to that of the Father, and that Father and Son have the same substance" (homoousios). Athanasius' teaching was a major influence in the West, especially on Theodosius I. On 28 February 380, Theodosius issued the Edict of Thessalonica, a decree addressed to the city of Constantinople, determining that only Christians who believed in the consubstantiality of God the Father, Son and Holy Spirit could style themselves "catholic" and have their own places of worship officially recognized as "churches"; deviants were labeled heretics and described as "out of their minds and insane". Recent scholarship has tended to reject former views that the edict was a key step in establishing Christianity as the official religion of the Empire, since it was aimed exclusively at Constantinople and seems to have gone largely unnoticed by contemporaries outside the capital. For example, German ancient historian writes that the Edict of Thessalonica was neither anti-pagan nor antisemitic; it did not declare Christianity to be the official religion of the empire; and it gave no advantage to Christians over other faiths. It is clear from mandates issued in the years after 380 that Theodosius had made no requirement for pagans or Jews to convert to Christianity. Nonetheless, the edict is the first known secular Roman law to positively define a religious orthodoxy. According to Robinson Thornton, Theodosius began taking steps to repress Arianism immediately after his baptism in 380. On 26 November 380, two days after he had arrived in Constantinople, Theodosius expelled the Homoian bishop, Demophilus of Constantinople, and appointed Meletius patriarch of Antioch, and Gregory of Nazianzus, one of the Cappadocian Fathers from Cappadocia (today in Turkey), patriarch of Constantinople. Theodosius had just been baptized, by bishop Ascholius of Thessalonica, during a severe illness. In May 381, Theodosius summoned a new ecumenical council at Constantinople to repair the schism between East and West on the basis of Nicene orthodoxy. The council went on to define orthodoxy, including the Third Person of the Trinity, the Holy Spirit, as equal to the Father and 'proceeding' from Him. The council also "condemned the