Horsenell, the motives of these terrorists are known, although few countries want to admit that they are politically motivated attacks and have very little or nothing to do with religion. These terrorists believe that they can frighten Western nations into withdrawing from Middle East countries like Iraq and Syria by using terrorist attacks. Obviously they can't. A second motive is to try to divide people to gain power over them.  That works in some cases as some people tend to try to blame all Muslims for the actions of the few. 
Approximately a billion and a half people around the world practice the religion without wanting to kill anyone, so obviously it's not the religion that's the problem