For the rest of this. I don’t think this forum is the place for current political/social commentary at all. And from my experience lurking the mods tend to be strict about these sorts of things so I think it’s best to keep our discussions strictly about the time period.
Now sir, I wasn't making a value judgment, I was merely stating my observation of the behavior of different demographics. Cities are breeding grounds of revolutionary ideas and behaviors simply by nature of the proximity of people living in them, which is a big part of what lends people in them to turn on a dime like that. Ideas just don't disseminate to the countryside in the same fashion. Those are changes I've observed in my life time that at first glance boggled my mind, but once I had connected the dots as to why people in cities behave differently from people from more rural areas it made perfect sense. Another thing I would say about these differences is that the sheer volume of people in cities puts people in an environment where their minds are overloaded with too many potential social bonds, so they have to learn to tune people out to a certain extent. This is why country folk like myself have often observed that people in cities have a tendency to be colder and more aloof than people in the countryside, and the ironic social isolation that such information overload causes means that it is easier to change your opinions radically because you don't have the same network of people holding you to a set of values for the survival of your social group. To be concise, living in the country selects for greater sociability because the number of relationships one has to manage is much smaller, and living in cities selects for more individually minded, introverted people because the number of relationships to manage is overwhelming.
How does this pertain to the timeline? Well, I don't think that it would take people nearly as long as we all looking back in a post-Christian world like to think it would to drop Christianity. I think that it would take a couple of generations, but only because of the limited capacity for ideas to travel at the time. When Radagaisus was marching on Rome to sacrifice the Senate, the Christians in Rome suddenly became very devout Pagans and abhorred the name of Jesus until they got the news that Stilicho, himself a Christian, had swooped in and saved the day. Christianity at this point was almost entirely an urban phenomenon most heavily concentrated in the urbanized Greek East. The way that ideologies fluctuate easily in urban environments leads me to believe that this could happen very quickly, in less than a century. Look at how popular fascism and eugenics were in the late 19th and early 20th centuries amongst sophisticated urban folks and then consider what actually advocating such ideas would get you here or on any Subreddit.
I don't think it's set in stone really that there would even be Christianity in general within 200 years of the POD, but I personally think it's more interesting to have it just fall slowly out of vogue and then be assimilated into the religious practice of Axial Age polytheism.
Regarding the period, I do think Christianity will be forced into the private sphere by the Julian legislation, just that once it’s done so I don’t really think there will be much done structurally after that. Christians will basically become crypto-Christians in the way that pagans became crypto-pagans OTL. For the vast majority of the populace OTL, there was no great struggle between Christianity and Paganism, and Christians as a collective had not inflicted massive institutional trauma to Paganism until the reign of Theodosius when bands of roaming monks invaded the countryside and smashed altars and images, despoiled temples, etc.
I think that increasing fundamentalism on the part of the Christian movement being consumed by internal division will beg state interference, either with the more intolerant sects being banned, forcing them into exile, or with edicts of toleration being passed that ban Christians from condemning other Christians, which will cause many of the previously popular brands of Christianity, specifically those with a High Christology, to purity spiral behind closed doors, leading to the rise of Low Christology, Christianity-lite varieties taking precedence. This is probably what informs the movement to assimilate Christianity into Mesopotamian religion as Buddhism is also going to be floating around, which will lend to the Docetist idea of the Christ as a Spirit that comes over man.
I think that based on historical models there would be a period of ambivalence to Roman religion and institutions, followed by a period of tacit reliance on them which will over time transmute into an adoption of said Religio Romana in ways that specific suit Germanic culture and their own traditions of the warrior king and his elite band of nobles from whom he derived legitimacy (before the Alan’s/Franks/whomever are finally assimilated, only remaining as a warrior elite-nobility who lend their name to whatever new kingdom they’ve formed). Sometimes this might even seem to be contradictory, the Carolingian Frankish empire derided ethnic identifying Romans while also claiming the mantle of Emperor of Rome for example.
I think you misunderstand how polytheism works, sir. You seem to be modeling the development of Germanic religion here off of the conversion to Christianity in a post-Roman Europe. There are two problems I see here. For one, the primary focus of polytheism is orthopraxis, not orthodoxy. Many people have many beliefs about the Gods and tell many different stories or different versions of different stories, but that doesn't really affect how we interact with them or that certain Gods demand our respect. When I tell people that I'm a Pagan and they ask what that means, I say that I worship my Elders and their Gods. When telling people how to begin with their Pagan practice (and I'm still learning myself, of course), I tell them to start out with the Gods of their Elders, but to be open to any Gods that might call on you or that you might be interested in from other pantheons for whatever reason. I worship Freyr, Freyja, Frigg, Óðinn, Loki, Njǫrðr, and Cernunnos (who I call An Dia Adharcach), but I also worship Ogma and Saturn (on occasion), Hekátē, and Antínous. My worship of Greco-Roman Gods does not get in the way of the worship of the Gods of my Elders, because as long as I worship my Elders, that link to those pantheons (Germanic and Celtic) isn't broken. We see this in East Asia with Buddhism as well. The Elderworship is an integral part of their religious practice, and as long as correct practice (orthopraxis) is upheld, it doesn't really matter that the people generally identify as "Buddhist", they still participate in their own traditional religion.
So no, I do not see this happening at all. Furthermore, I'm far more interested in the idea of Scytho-Germanic civilization developing in contrast to the civilization of the Mediterranean for ideological reasons. I've been mulling over the idea of Hun chieftain actually conquering the Roman Empire wholesale and behaving like Chinggis Khan/Nurhaci, establishing a Hunnic dynasty, suppressing Greco-Roman culture for over a century and moving multiple different population groups around before a popular backlash that kicks them out after said empire breaks up. The new Roman dynasty would be like a heavily fundamentalist Roman Ming dynasty, and Europe would be divided into Europe and Barbarica to the north. I also think it would be cool to have all the holy relics of of Ancient Rome removed when the Huns raise the city to the ground and have them dragged to their capital, only for them to be fought over and redistributed gradually bay various different successors and successor states. Thus, in Barbarica and Europe alike, stories surrounding these relics would abound. Who has them hidden where, how some were destroyed or lost, others were repurposed. In Europe, stories would be about emperors, generals, and heroic adventurers who penetrated deep into Barbarica to recover them. I can imagine for example the Ancile being melted down into a series of hilts to sacred swords. Perhaps only some of them have been, and others yet still remain. There's a lot of possibilities here, but it makes for a fun narrative representing the clash of the two different civilizations, I think.
Now that I'm thinking about it, I very much like this idea, actually. It could play into an interesting interplay between in Europe in general in terms of culture, religion, philosophy, and language. Religio Romana might get increasingly Egyptified, as Neoplatonism and specifically Iamblichan Neoplatonism was extremely so already, I would argue. Europe might then see Egypt, Greece, and Rome then as the Three Fingers, that is the Three Fingers of God held up in the benedictio latina hand gesture that was common in the imagery of Sabazios-Dionysus, which of course was very much part of Mithraism as remember Mithras is the one who KILLS Sabazios-Dionysus to restart the Cycle of Being, or in this case, the year. The bull being sacrificed in the tauroctony scenes in the Mithraea are representative of Sabazios, who may be equated with the Egyptian Apis Bull. In fact, it does seem that these myths were analogous, as the Bull was thought to be sacrificed at the end of every year in Egypt so to resurrect again as Osiris so that the Cycle could continue. Within the Mithraic imagery, likely of Thracian origin, the Bull is being sacrificed to rise again as Zagreus. Remember that the name Zagreus itself refers to a pit for capturing animals, and he is said to have been ripped apart by the Titans as a child. Here, we might interpret the imagery as possible justification for offering up a bull instead of a youth as a sacrifice, which may then become equated with the myths surrounding Antínous and his sacrifice to save Hadrian's life when he was ill. The Cult of Antínous was widely popular at the time and a competitor to Christianity, especially in the Greek East, and there were places in which he was already equated with Apis-Osiris. So then, we might see the development of special ritual sacrifices of youths who are selected for such a purpose develop in Europe and perhaps also Barbarica in times of dire need instead of the sacrifice as a Bull, which acts as a stand in during times of plenty. Anyways, the Three Fingers of God come into play here as Zagreb's, Dionysus, and Sabazios are scene as symbolizing the Cycle of Being and thus Being Itself, and they are identified with what are believed to be the Three Nations that represent the Three Stages of Formation of European Civilization, being Egypt, Greece, and Rome. In Barbarica, there would be a similar belief (Antínous was widely popular also in Gaul, where he was equated with Belenos), with the Three Nations being Celtic, Germanic, and Scythian. They would see themselves thus as mirror images of each other, and this could feed into various esoteric doctrines surrounding the Nature of Being, where the two civilizations being mirror images stand opposed to one another, with one side needing to break through the other to attain Unity with God, whilst later a doctrine develops of the acceptance of opposing categories in a sort of Yin and Yang fashion (this will probably start in Barbarica) and even later still, one of peace between the two that believes that the acceptance of the image of oneself in the mirror as being part and parcel of the Body of God is necessary for Enlightenment/Henosis, which may itself develop in Europe.
Just an idea, though...