I dont think so that ISLAM itself responsible for terror, or failed to spread the peace. If some people make a group and start fight against the world, then they clearly deny the actual techings of Islam. Islam never preach to kill ANY one due to ANY reason. There are some reasons behind such extreamist groups like Afghan War. Everyonw knows so many millitants join Taliban in the reaction of Afghan war. Same in Iraq, the instability is still exist both countries. So these are the reasons which is somehow true. But still i said EVERY person who killed any other on the name of Islam, not on the right way.