The idiot prophet was illiterate. The "word of God" was put to paper by his assistant, who could write recipes, for all the prophet knew, and he would be blissfuly unaware.
The stupid "hadith" contains stories presumably about the prophet (sbuh), personally, which numbered into the "600,000 (!)", before al-Bukhari, (full name Abu Abdullah Muhammad bin Ismail bin Ibrahim bin al-Mughira al-Ja'fai), in the 9th century, "narrowed them down" to 7275, or 9,082, depending on whom you choose to believe. All by himself. So in essence we have to trust al-Bukhari, for having gotten it "right".
One gentleman, called Ibn Abi al-Awja, who was put to death in Iraq in 772, confessed before his executio to having made up more than four thousand of them!
My main point being that these perfect, inviolate words of "god", written by god himself eventually allowed 590,000 of the "sacred" Hadith stories to go missing.
Satanic verses, anyone?
the old Testament was once considered national law too. Eventually it became a voluntary law of holiness.
Islam is submission, but to Allah. That is different from submission to any particular human who claims to be his mouthpiece or prophet.
There are several schools of interpretation of the Qu'ran and the Hadith. The Wahabi heresy is well funded, but attracts a very small minority of Muslims. Iran is Shi'ite, but the largest Muslim nation is Indonesia which has even had a female president.