I am from Indonesian which many of mosque used star and crescent symbol. FYI this symbol appears in our Mosque just after the Dutch Colonialism came over my country for 350 years. before..The mosque didn't use this symbol..Do You Know WHY??Because this symbols mean: "Keep Fighting, Keep Struggling, never Give up, keep trying even for hundred years" just like the Sultan Muh. Al Fatih and his troops did in Conquering Constantinopel. For 800 years the muslim try to Conquer Constantinople, Why?..because it is the Gate to spread Islam to Europe.
Estimates of the number of Sufis in Egypt include at least a third of the adult male Muslim population in Egypt, (six million men) being members of a Sufi order; fifteen million of the country’s roughly 80 million citizens "claim" Sufism "as a practice",  still another says while 15 million are registered as Sufis, "the true figure is likely to be higher".  Participation at the festivals ( moulids ) the Sufi orders organize, is perhaps twice that (and includes women and children).  The moulids are a major manifestation of Sufi Islam in Egypt, and are held in honor of holy men and women. (In Egypt the term Moulid is not reserved for Muslim festivals and may be in honor of Christian, and until recently Jewish holy men). Sufi Muslim moulids not only venerate the prophet Muhammad and his descendants (such as Hussein , the second son of the fourth Caliph Ali whose moulid in Cairo can draws crowds of more than a million people), but founders of Sufi orders, down to dozens of lesser-known sheikhs celebrated mostly in remote rural communities. The largest moulid in Egypt takes place in Tanta , the largest city in the Nile Delta , and draws an even larger number of pilgrims than hajj in Mecca. As many as three million Egyptians and other Arabs gather there every October to celebrate the life of Sayid Ahmad al-Badawi , a thirteenth-century Sufi leader.  According to the Egyptian Ministry of Awqaf (Islamic charity), there are officially more than forty such annual commemorations, and the Sufi Council in Egypt lists eighty other festivals for lesser-known founders of Sufi orders. 
The answer is neither. They are not exceptions, nor do they speak to a violence inherent in Christianity. Because my point is not that Christianity is evil. It isn’t. But neither is it inherently peaceful and loving. And neither is Islam. Nor Judaism nor Hinduism nor Buddhism. No religion is inherently peaceful or violent, nor is it inherently anything other than what its followers make it out to be. People are violent, and people can dress their violence up in any number of justifying causes that seek to relieve people of their personal responsibility because the cause or religion, be it Communism or Catholicism or Islam, is simply bigger than themselves. It’s very convenient for both the perpetrator of violence and his accuser, and yet totally useless: Something can be done with a person who has transgressed, but what can you do with an amorphous concept?