The right to burn a Koran is not the main issue. The key issue is whether we are free to conduct research, and to publish conclusions like this:
[Sven] Kalisch, . . . scandalized the Muslim world with a 2008 paper claiming that the Prophet Mohammed was a figure of myth . Citing the work of Western Koran critics, Kalisch claimed that the prophet's life was the fabrication of 8th-century apologists:It is a striking fact that such documentary evidence as survives from the Sufnayid period makes no mention of the messenger of god at all. The papyri do not refer to him. The Arabic inscriptions of the Arab-Sasanian coins only invoke Allah, not his rasul [messenger]; and the Arab-Byzantine bronze coins on which Muhammad appears as rasul Allah, previously dated to the Sufyanid period, have not been placed in that of the Marwanids. Even the two surviving pre-Marwanid tombstones fail to mention the rasul.
Islam, he concluded, was a revival of the old Gnosticism expunged by Christianity and embraced instead by the Arabian tribes.
Mythology of not, according to an account I read in a college comparative religion textbook, Mohammed selected one god from the Arab pantheon which most suited his purpose, which was to destroy the Judaic and Christian religions which had come to dominate the Arab world in his time. Allah demands absolute, unquesioned obedience and a display of piety dwarfing that granted to other gods. As Pope Benedict observed last year in a lecture in Germany, Allah is unbound and beyond reason. For his purposes, Mohammed (or the clerics who invented him?) chose well.
Mythology OR not
Paul Johnson: https://books.google.com/books?id=mv0grelUicsC&lpg=PP1&ots=kh2Pue9cDd&dq=History%20of%20the%20Jews&pg=PA167#v=onepage&q=Mohammed&f=false
Not the same, but rather saying that Islam is an adaptation of Judaism, "to destroy the polytheistic paganism of the oasis culture by giving the Arabs Jewish ethical monotheism in a language they could understand and in terms adapted to their ways." The Koran certainly adopts some of Jewish tradition, more than makes sense if Allah is an Arab god.