Muhammed(pbuh) did send a letter to Heraclius. What if Heraclius wanted to know more and invited the prophet? Maybe he could have convinced him to convert to islam, if they met face to face.
Persia and Zoroastrianism are too deeply tied. There's no way I can see the Persians converting to Islam.
Most plausible case is the successful Arab conquest IMO. Persia converted because it was conquered and ruled by the Caliphate for a long period of time and then shifted to local rule under Muslims, so the same process could occur in “Rumelia.” In this ATL you’d get a “Roman Rebellion” to kick out the Arabs, probably during a civil war.
Alternatively, you could just have a Byzantine Empire that survives till the modern day, starts liberalising, and eventually the acceptance of both Christians and Muslims in the Empire makes the faith of the Emperor rather irrelevant (partially because it is a ceremonial position - but could be an executive) - and so it happens that you have a chain of Emperors that go Christian-Atheist-Muslim-Christian-Muslim-Muslim-Christian-Atheist, etc.
If we assume we aren't going to see a mass conversion of the Muslim world in a late-Roman-Revival scenario, then eventually tolerance could win out and lead to that secular tolerance
It's an interesting point of view, however don't think it could be done without tensions. The US is supposed to be secular and see all the issues around Barack "Hussein" Obama... Or for that matter, imagine if the Queen of England converted!Alternatively, you could just have a Byzantine Empire that survives till the modern day, starts liberalising, and eventually the acceptance of both Christians and Muslims in the Empire makes the faith of the Emperor rather irrelevant (partially because it is a ceremonial position - but could be an executive) - and so it happens that you have a chain of Emperors that go Christian-Atheist-Muslim-Christian-Muslim-Muslim-Christian-Atheist, etc.
If we assume we aren't going to see a mass conversion of the Muslim world in a late-Roman-Revival scenario, then eventually tolerance could win out and lead to that secular tolerance
That's pretty neat. Have a resurgent medieval Byzantium, then have it reform to a more secular state. Perhaps even have a Copt Emperor.
It's an interesting point of view, however don't think it could be done without tensions. The US is supposed to be secular and see all the issues around Barack "Hussein" Obama... Or for that matter, imagine if the Queen of England converted!
might cause... difficulties. Not saying it's impossible though
Yeah, but there's still a difference between different flavours of Christianity and becoming Muslim. Obviously, as you say, timelines, butterflies and all...Well, regarding the Queen, we've had a lot of changes recently, including changes to inheritance law, but also active discussions over the role of being Catholic or Church of England! - I have no doubt that it would likely require decoupling the Emperor from being the head of the Church - the title of Vice Gerent of Christ might remain, but with the Church being independent of the State. Otherwise the same problem emerges.
It might take till 2200, but it'd work, eventually.