September 11th is an important day for a number of reasons.
First of all four planes were hijacked nine years ago and thousands of people murdered. Hijackers, mostly from Saudi Arabia, were inspired by a twisted form of Islam to “martyr” themselves to bring holy war against the US and non-Muslims in general.
Secondly, a load of religious fucknuts are burning a bunch of Qu’rans in Florida somewhere. The congregation, mostly from moronsville, are inspired by a twisted form of Christianity and Nationalism (although they are not quite in Osama’s league of course).
Chile not withstanding, perhaps most important of all,  Eid starts on the 10th September this year. A huge feast to celebrate the end of Ramadan. It is a pretty big deal and as a three day festival will continue throughout the 11th September.
Because the Islamic calender works on a lunar year the month of Ramadan shifts back each year. A few years ago it coincided with Christmas and now for the first time it coincides with an event, which for better or worse, many people now associate with all Muslims.
I predict that someone somewhere will point to Muslims feasting on the 11th September and say “Look! They’re celebrating 9/11!” I hope it doesn’t happen, but there has been a growing level of hostility towards Muslims recently, especially in America, and it would fit with the general misinformation and malfeasance.
 I’ve said “probably most important” because in aggregate, being quite important to billions Muslims for over a century millennium probably puts Eid up there with the most important things ever, not for me, but for many people. .