I'm an atheist. However, I have studied all three Abrahamic religions. Mohammed started the fuedl. In Jewish history, he went to the Jews and asked them to start a new religion with him as it was a great way to make money (what's changed?) and they declined the offer. He wrote the Koran and his wrath shows. He also had a problem with Christians 'as they accept no religion bar their own.'

That's where it comes from. Like I said, read the Koran, then read the secular history of Islam.