Simply , They Don't understand true Islam ...
I'm Muslim and proud of that ..I live in Egypt .... I didn't harm anyone ,,,, I've Christian neighbours and they're my brothers .. my teacher is Christian and he treats me as his son ....
I do everything that Quraan asked us ... we don't attack anyone but when he attack us , we must save ourselves ....
Don't trust those who say that Islam is related to terrorism ... plz .. in 5 mins of ur time read this :
http://www.tafsir.com/default.asp?sid=2&tid=4985