Because history records it as such, that's how I know. If I were completely ignorant of history as you are, as are most of the billion Muslims who have been taught to believe an alter reality, I wouldn't know it... I would remain ignorant and stomp my little feet and insist you listen to me. But since I understand the time-lines, and the events which lead up to Mohamed and the creation of Islam, and since I comprehend that Moses and Abraham were NOT indeed Muslims, and that it is nearly impossible to believe the supposed lineage from Abraham to Mohamed, as it requires you to believe people could live for 2,500 years before having children and such.... I have to 'side' with the Jews and Christians on this one... especially since their version predates Mohamed's version by a few thousand years, at least.
No, it's not plausible at all... it's quite preposterous.
Be clear... the Muslims have wanted to exterminate the Jews since the inception of Islam, not merely since 1948. Again, history is FULL of record on this, and it's not disputable among intelligent people. It is only the ignorant of history, and misled Muslim followers who believe otherwise. You are also wrong about the "radicals" or "tiny number of extremists" as I have also pointed out... this is the basic tenant and foundational purpose of the religion itself, the condemnation, opposition, and ultimate annihilation of the Jews. ANYONE who is a practitioner of the Islamic faith believes this, or they are not being honest about what they believe. That is most certainly a possibility, as one of the tenants of Islam is Taqiyya, the practice of LYING to the rest of the world about their motives and objectives, in order to further the greater cause of Islam.