It is not really that they want one thing. They think that we are downright evil. They use religion to justify their actions. They think that they will be rewarded in the after life for killing people in the west. That brain washing is just horrible.
I agree that there is some terrible brain washing going on. The sad thing is that they are only bringing shame and disrespect onto their religion. Here in England, once a very tolerant country, there has been a shift towards the view that Muslims are to be feared. This is purely down to the actions of terrorists.