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I was thinking about a 530s POD which affects the rulers of the area of Persia and the Levant to make Oriental Orthodox Christianity popular among the higher class and have it maintain there after muslim conquest. Or rather in TTL, it would be the local rulers submitting to the Muslims in exchange for autonomy and some concessions.
I want some places to develop similarly to OTL. ...The most annoying is the Holy Roman Empire, Scandinavia, Iberia, and England. Those that have a land connection that is easily traveled to the area affected by the POD (as opposed to Egypt where long distance travel in the south happens little at this time, even on the Nile only intermittently and low volume). How can I keep events in that region very close to OTL plausibly for 600 years?
How are those mostly western regions tightly bound to the Levant, let alone Persia, by a "land connection" anyway?
Western Europeans had a long history before the Crusades of pilgrimage to "the Holy Land" as they thought of the Levant region, so they certainly would have a long sequence of personal eyewitnesses on the ground to any changes there but I don't see how your POD really changes much for them, or for Vikings or later Nordics and English such as Varangian Guards, nor would the development of the Rus seem much affected by still distant Persia. The Levantine taste for Orthodoxy ought to have changed some aspects of how the Arabs took over under Islam, which I presume you have unbutterflied too, since OTL the generally non-Orthodox sympathies of most of the Christian population of the southeast Empire had a lot to do with how easily it fell to Muslim Arabs--you do say it is the elites who align more with Constantinople (that is what being "Orthodox" in 530 would mean after all) so perhaps the disgruntled commoners opening the gates and joining to serve under their new lighter Islamic yoke still has the same broad upshot.
600 years takes us to just 100 years after the Crusades started OTL. I think given the subtle change in the Levant and that until the Crusades, western European pilgrims will be little differently affected, keeping Latin Christendom unbutterflied is an easy ask. I still can't fathom what you mean by "close land connections."
You aren't confusing the Byzantine Empire with the Holy Roman Empire, are you? If you meant Constantinople instead then suddenly it makes a lot more sense--the Roman Empire as they called themselves would surely try to exploit what opportunities Orthodox, which is to say Byzantine loyalist, sympathies in "upper class" circles in both Levant and Persia of all places might offer them versus their Islamic led foes. Which raises the question of how, in the face of that sort of conflict, "upper class" residents of either region could remain both Orthodox and upper class, or even left alive--Muslims did not as some nuns in my Catholic school years suggest "put people to the sword" nearly as much as Sister Mary Thomas suggested, but surely this degree of disloyalty, conniving directly with main enemy of the various Caliphates, would draw unpleasant attention and they'd be subjected to stronger pressures than normally applied to other Peoples of the Book who adhered to some non-Islamic Nazarene tradition that happened not to be the communion of the cursed Satans of Rum itself! Orthodox congregations were indeed tolerated under most Muslim rulers, but I believe a price they paid for that was being excluded from the higher socio-economic elites of the regions in question. So something probably has to give somewhere, not for butterfly but systematically logical reasons. For Persia to first go Orthodox at the last minute and then stubbornly adhere to that rather than revert to adhering to Zoroasterianism strikes me as improbable and very odd too. Why should they suddenly revere the Roman tradition, when the entire history of Persia is one of opposition to the Hellenics and Latins? Does Justinian enjoy some kind of super wank victory and is also blessed with some sort of ATL halo of glory and benign image that makes the elites (just the elites mind, no word about the greater masses) Romanophiles, so strongly so that when all the institutional supports of such an alignment are yanked out from under them via the Islamic conquest, it is Roman(that is to say, Byzantine Orthodox centered in Constantinople) Christianity they adhere to rather then the ancient religion of their ancestors to spite the Muslims? Very very strange!
Indeed given the sort of titanic and not very probable seeming precursors such a strange outcome would seem to require, you probably should give in to loads of butterflies and let the whole world become strange. I can see an Eastern Roman victory, improbably but not impossibly, getting a brief hegemony over Persia but I don't see how it could be so well received as to make the elites persist in Orthodoxy versus the strong deep current of Islam and the deep roots of their older religion, which the Muslims, though somewhat persecuting, did recognize as a People of the Book valid old faith and unlike Christian Orthodoxy would not be aligned with their current number one enemy. And if somehow this were conjured into being presumably the next 600 years of the Eastern Empire would be different, always probing and prodding at the opportunity to return to both Levant and even Persia, or if reconquering Persia is out of the question, then subverting Persia to an unholy alliance against the heartland of the various Caliphates centered in Mesopotamia.
I still say that the western and northern Europeans you singled out for attention, including the successor to Charlemagne's claimed restoration of the Western Empire, could survey all this deviation from OTL from afar, and pilgrimage right in to the middle of it, and still come out much as OTL, as late as the twelfth century. Now by then the alternative experiences they would likely have in the Crusades, which might happen right on schedule if a suitably fanatical Islamic purist Caliph arises in Egypt to strive to purge the Levant of what he deemed unorthodox--this was the OTL trigger along with a Byzantine appeal for military assistance in the context of a brief rapprochment between Constantinople and Rome. It would be possible to arrange parallel events emerging from a different history, and set up the Crusades as at were an armed pilgrimage to"liberate" the Holy Land.
Given the 600 year span after 530, I suspect what you are trying to set up is precisely a stronger Latin incursion into the Levant--more successful Crusader states in other words.
If that is the goal--let me suggest this:
The Levantine and more oddly Persian upper class Christians are not "Orthodox." They adhere to some rite that the Orthodox revile as heretical. OTL when the Crusaders came in, they typically honored Palestinian Christians of many rites, and forged official confessional ties with various sects that were quite different in doctrine from the Latin rite--but the important thing to the Latin "Franks" was not that they agreed in doctrinal matters and ceremonial practice, but that they did not gainsay the authority of the Pope! They could deal with all sorts of heterodox stuff as long as the rite did not declare itself in opposition to the Roman Papacy. Whereas the Latins mistreated actual Orthodox faithful quite badly, stealing their church buildings and so forth, because while doctrinally they were much closer to the Roman rites than many of the "Frankish" native regional Christian allies, their rite specifically denied the supremacy of Peter's line in Rome, and despite the fact that it was an Emperor of Constantinople who first invited the Crusaders in in the first place, they were generally at war with the Eastern Empire quite as much as with the various Caliphates and Turks and so forth.
So--if your stratum of ATL elite persistent Christians are some rite that is opposed to the Orthodox, it does not matter how divergent they are from Latin rite Roman orthodoxy in doctrine--the eventual Crusaders will love them just fine, and champion them, and you can have a stronger Crusader kingdom and what not with their help. Whereas, the fact that they were not aligned with Constantinople helps make their influence more consistent with OTL patterns of Islamic early victory, and helps explain how they can keep a respectable rank in a Muslim dominated region while remaining Christian--they are not inherently traitors by doctrine, they hate "Rum" too! It all comes together if you make them not-Orthodox. It is paradox on paradox if you make them Orthodox.
You might be going for something completely different of course and then maybe Orthodox works, but I don't see how they can persist as wealthy elites in the Islamic sphere being openly aligned with Constantinople's emperors.