I am surprised and a little sceptical of the tens of thousands figure. You have two dozen in the 9-11 attacks, a half dozen to a dozen each, in the attacks in France, Belgium, England and Germany.
Every once in a while, a group goes a little bit off the rails. Hindus massacre Muslims in the thousands, Buddhists massacre muslims, Christians massacred the entire population of Jerusalem, Soviet and Maoist atheists murdered tens of millions. On the day I was born, Jewish terrorists murdered British soldiers.
The name of the religion has nothing to do with the act of terrorism. With the exception of the war between Sunni and Shi'a Muslims, Islam has maintained a fairly peaceful existance. Its relationship with the west during the latter half of the twentieth century was quite peaceful. Did the theology of Islam change in 2001? Or is there another reason for the sudden surge of attacks for which religion of any label is merely and excuse.