^911 happened because, as Ron Paul said, "We have been over there, bombing them for 10 years."  I think our foreign policy is the reason that they came over here, religion was just used as a tool to get more followers.
That said, Hitler, Mussolini, Stalin, Mao, and Pot were all atheist dictators who killed literally hundreds of millions of people.  (Yes Hitler was Atheist, I hate how people try to argue that.)  Oh and lets not forget the amount of people who died in the wars that these guys started.  When the death toll of people with religion can even compare to the numbers that these people brought, I may change my view that religion does not kill people, unless it is used as a tool when used in the wrong context.
Religion is not to blame for hatred and war, it is mostly to blame for forgiveness and ending wars.