If Muhammad's letters are 7th c., who used them?

Concerning the letters of Muhammad (i.e. the Ashtiname), Rajiv Abraham comments, “If this letter were authentic, it would be mentioned by Mohammed himself or his companions at least in the Sahih hadiths. Muslim Caliphs would have known that there are limits to what they can do vis-a-vis Christians, Jews and Zoroastrians as this would have been their template for conduct towards other religions. The fact is that many Muslims are hearing about this document for the very first time. Also, many other Christian churches, Jewish and Zoroastrians would have copies of this or at least would have been aware of this document. Especially if it was mandatory for their own survival. Besides Mohammed would have come across as a compassionate and trustworthy human being who kept his word, which would have been a role model for Muslims all over the world. Muslims would have been holding up this as an example to show that Islam was indeed a peaceful religion. Obviously this document is a fabrication”. Rajiv has 'hit the nail on the head', because if this was a real document, then it would have been known right across the Christian World, and used as a protective for the Christians being persecuted and attacked by Muslims right up through the 16th century. Even the Jews would have wanted a document like this to protect them. Yet we hear of nothing about this until the 1500s, during the reign of Salim 1, who was well known for persecuting Christians. Ironically, this document has only recently been popularized since the '911' incident, because now Muslims are more desperate than ever to prove that they are a religion of peace. And that is why Dr John Morrow wrote a book on it, trying hopelessly to prove it was authentic. And for what reason? Because it's obvious you can't go to the Qur'an to find peace, what with the over 160 violent verses throughout its pages which are considered authoritative for all time and all people. And you can't go to the example of Muhammad, especially when you see what he did to the Jews in Medina between 624-627 AD. Since they have no other authority to go to, they have to depend on letters such is this one, created centuries after the fact as a ticket for freedom for the poor monks in the St Catherine's monastery. I can understand their dilemma, because today everyone wants peace. However, if you really want to find a document which will support and authorize peace, then you better not go to the Qur'an, nor to the prophet of Islam who supposedly received it; you had better come on back to the Gospel of Jesus Christ, and to his example, the true paradigm of peace. "Come on home" © Pfander Centre for Apologetics - US, 2020 (27,960) Music: "small adventure", by Rafael Krux (from filmmusic-io - License CC BY)