No group, no people, no institution, no religion, has ever (until the last few hundred years)denied Har Sinai. Even though the Jew has been the most hated of all peoples (you might want to think about why that was)and their religion the most hated of religions, no one could deny Har Sinai, even though they would have loved more than anything else to do so.
Why?
Because it was STAM HISTORY. It would be like trying to deny that Abraham Lincoln ever existed. It was plain and simple FACT.