So before today my understanding of the origins of Islam was something like this. There was a man called Muhammad and as well as being a trader and something of a raider of caravans across the desert, he was intense and had these revelations, first of a more general kind and then of a more managerial kind. He told them to friends, but several versions of the Qur'an existed over time and these were brought to one. He married later on for tribal reasons. He built a tolerant city of Madina but had a problem with the local Jewish opposition, and an embarrassing episode is him attacking them when seen as a disloyal opposition. After his death this communal Islam then spread by Arabs forming an empire, even a motivation of their expansion. Some of my information is from the PGCE RE work, my own reading, and the over-generous Karen Armstrong.
After Tom Holland's piece on Channel Four, I'm bound to make adjustments - with the proviso that there have been a number of wacky programmes about the origins of Christianity on Channel 4, with different explanations of resurrection for example that do not stand up to scrutiny. I do not for example think that Jesus was given healing herbs and survived death and met his disciples before getting outside the Roman Empire in a search for the lost tribes. And no I do not believe in an objective resurrection of any kind and can explain it from the material available (as can anyone).
Taking his word for it, then, there is the first problem that the victorious Arabs at Jerusalem do not bring an identified Islam with them. There is no imprint as there was with the other religions. The Arab victory continues with two religions functioning properly (and Zoroastrians): the Jews find more tolerance.
Then there is the absence of the qiblah in the right direction, though that can have other explanations. Mecca does not get a proper mention in the Qur'an either. The question then is the whole story of Makkah and Madina, as already stated: what about how Madina was ruled by Muhammad? It's not all to his moral credit, nor is his continuing attack on camel trains. Karen Armstrong is far too apologetic on this. If this is not historically grounded, how did it arise? I'm quite clear that Abraham didn't exist never mind went to the desert and establish Islam in the Ka'aba, only to have the Pagans corrupt the attempt. The story of the miraculous spring is a nonsense to my historical ears.
Then we have the encounter with peoples, and here Tom Holland is quite convincing, in that the people are conversant with Christianity and Judaism, indeed we suspect he encountered Ebionites and the more primitive tradition of Christians than the Pauline, though again that needs caution. Distinctions are made between the love-meal of early Christians and a Pauline eucharist, whereas the simpler celebration might also be an economy of persecution and anonymity. But it gives questions to the geography of origins, say in Syria where the olives grow, though again people travel. He's weak on the first sanctuary at the foot of the Dead Sea, and he knows it - but the general point is well made.
Same with the coin and it drawing on Muhammad. Abdul Malik continued to use Islam after defeating the first warlord to draw on the power of this prophet to bind people together. The first coin is some 60 years after the death of Muhammad. We do often say that the Arabs wanted a religion of unity like the Christian and the Jewish, but of course this was set on understandings much earlier in Madina itself.
I have assumed that more was known historically about Muhammad than about Jesus, but I think this is up for revision. There is indeed a 'black hole' but then it could be because Muhammad was deep inside a spread out, transient, on the move, society. The Hadith about Muhammad is, of course, told and created. Buddha is lost inside texts of traditions but some stripping away is possible based on assumptions. We know considerably more about Baha'u'llah of the Baha'is and then most by far about Gandhi.
Rules of historiography apply to Islam as much as they do to any other religion. But also one can read the contraditions in the Qur'an and the mistakes - e.g. about the Trinity (an evidence of getting it from a different Christian group). The Qur'an is in non-historical order - I have a version in apparent historical order - and can be confusing. Many Muslims learn to recite it in a language they do not understand and as such have never read it - a situation comparable to the Bible in Latin read by priests and never distributed among the laity. But then Christians read the Bible and skate over the contraditions in the New Testament, simply because they listen more to authorities than read it themselves, and some of these preachers are like snake oil salespeople - keep quiet about what we learnt at college, like the salesman of a product who knows how it was made but presents according to the packaging.
So there is a programme on TV that has caused me to change my mind and to pursue the matter further. Tom Holland has his own response to criticism.
We have a Gospel to proclaim! - “God is an intelligible space whose centre is everywhere and whose circumference is nowhere. God is within all things, but not enclosed, outside all things...