There is plenty of evidence, a great deal in fact. This doesn't constitute proof, you can disagree with it if you like. Some Western academics disagree with it. When you say there is no evidence though you are displaying either ignorance or bias.
I personally find the evidence very persuasive, based both on the text of the Quran and the historical reality of the Late Antique Middle East. Arabia was not this distant far off land, and Christian Arab tribes had been providing large parts of the forces for the Roman and Persian armies for centuries. There had also been Jewish v Ethiopic Christian wars in Himyar in the 6th C. Early Muslims were said to have gone to the Negus of Ethiopia (a Roman client), early Muslims were said to have used Roman siege weapons and tactics suggesting some of the forces had previously fought with the Romans (which is almost certainly true anyway). One of the 4 hanifs became a 'viceroy' for the Romans, etc.
Early Islamic history for Muslims is theology, not academic history. These are 2 different fields and shouldn't be confused.
Medieval exegetes made up lots of things as they didn't know how to interpret passages of the Quran. Much of the sira was constructed around this. People couldn't even remember who the Sabeans were, one of a tiny number of 'people of the book'. Why should we trust them on minor issues? They managed to remember minutiae, but not something as significant as who the Sabeans were. Doesn't this seem strange?
Academic history is not an exact science, it requires educated guesses, assumptions and interpretation of ambiguous evidence. It rarely 'proves' anything, just offers up interpretations and descriptions with varying probabilities of being correct. And while your theology counts as evidence, it is not uncritically accepted and is treated the same as any other evidence and evaluated on its merits.
This is not biased, just a different methodology as used by Islamic theologians. If you prefer the theological methodology that's your choice and I have no arguments against it and no desire to challenge it (they are not compatible: one assumes God exists and intervenes, the other assumes God did not influence any of the events). I'm using the historical methodology and they are different approaches to the issue. Which one you prefer depends on your purpose, and mine is to examine the issue from using the methodology of academic history.
Good enough?
Al-i-Imran
Likewise confirming the truth of the Torah that is before me, and to make lawful to you certain things that before were forbidden unto you. I have come to you with a sign from your Lord; so fear you God, and obey you me. (
50)Surely God is my Lord and your Lord; so serve Him. This is a straight path".' (
51)And when Jesus perceived their unbelief, he said, 'Who will be my helpers unto God?'
The Apostles said, 'We will be helpers of God; we believe in God; witness thou our submission. (
52)
As-Saff
O believers, be you God's helpers,
as Jesus, Mary's son, said to the Apostles. 'Who will be my helpers unto God?'
The Apostles said, 'We will be helpers of God.' And a party of the Children of Israel believed, and a party disbelieved. So We confirmed those who believed against their enemy, and they became masters. (
14)
Al-Ma'ida
And when I inspired the Apostles: "Believe in Me and My Messenger";
they said, "We believe; witness Thou our submission."' (
111)
And when the Apostles said, 'O Jesus son of Mary, is thy Lord able to send down on us a Table out of heaven?' He said, 'Fear you God, if you are believers. (
112)
They said, 'We desire that we should eat of it and our hearts be at rest; and that we may know that thou hast spoken true to us, and that we may be among its witnesses.' (
113)
My argument: The radiocarbon dating could be correct, but the text most likely dates late 7th C at the earliest for the paleographic reasons that I gave as supported by eminent Western and Muslim scholars. Also supported by the evidence that radiocarbon dating is frequently wrong as Shown by Sanaa and explained by the noted difficulties of calibrating the machines for Arabia with tree ring data from Europe and America.
Your argument: The radiocarbon dating is almost definitely accurate because it was in the newspaper.
I stated the script was
evolving at this time. For example, diacritical marks did not exist in the 6th C.