Tarsonis wrote:The Archregimancy wrote:
I regret that this isn't wholly correct. Jovian supported Nicene Christianity, though it would be fair to note that his reign was too short to accomplish anything of significance theologically other than restore Christianity as the state religion.
The situation with the Valentinians is more complicated. Valentinian I and Gratian were Nicene Christians, so much of the Western Empire was under the control of Nicene emperors from 363 AD through Gratian's death in 383. However, the child co-emperor Valentinian II was initially dominated by his Arian mother Justina, which led to a complex dispute with St Ambrose in Milan. The usurper Magnus Maximus presented himself as a champion of Nicene orthodoxy against the Arian heterodoxy of Valentinian II and Justina Valentinian I's brother and Gratians uncle Valens favoured Arianism, so the (by this period) more important Eastern Empire was under the sole control of an Arian emperor until the accession of Theodosius I in 378. None of which stopped the Nicene Magnus Maximus from killing the Nicene Gratian, or the Nicene Theodosius protecting the Arian Valentinian II from the Nicene Magnus Maximus.
The relative toleration of the Nicene Valentinians towards Arianism and vice versa is likely down to the close family links within the family; Valentinian I and Valens seem to have placed family over theology. Once Theodosius was senior emperor, however, he felt free to make Nicene Christianity the official state version of Christianity (ignoring whatever objections the young Valentinian II might have had).
The short version is that it's certainly true that Nicene Christianity wasn't definitively established with Imperial support until 378, and that up until Jovian's accession in 363, most emperors following the death of Constantine were actively opposed to the Nicene definition. However, this wasn't true of all emperors.
However, even Theodosius I wasn't the end of the story. The defeat of Arianism (which would in any case flourish under the Ostrogothic, Vandal, and Visigothic states following the disintegration of the Western Empire) didn't mean the final triumph of what we would consider small-o orthodox christology. Several later Eastern emperors - most notably Anastasius I - were open monophysites. It's only the loss of Syria and Egypt to the Arabs in the 7th century that lances the monophysite theological boil; by removing the provinces where monophysitism (or, if you prefer, miaphysitism) was prevalent, there was no longer the need to come up with compromises along the lines of Heraclius's monoenergism or monothelitism.
So what the Orthodox, Catholics, and most protestants understand as small-o orthodox christology by no means enjoyed universal support by Roman Emperors until the transformation of the late classical Eastern Empire into the medieval Byzantine Empire was more or less complete.
We need to get you a bat signal, for when these types of disputes crop up.
Or rather, an Imperial Orthodox eagle signal.