The Qu'ran instructs Muslims that anyone who is not of Islam is an "infidel", and the Qu'ran states that infidels must be killed. A Muslim is not assured of salvation when they die, but according to their Qu'ran, the guaranteed way to heaven is to kill an enemy of Islam, meaning "infidels". Then, only then, are they assured heaven.
So if you are a Christian, a Jew, a Hindu, Buddhist, any non-Muslim, you fall into the ranks of the "infidel." So a Muslim has no qualms about strapping on a bomb vest and blowing themselves up, along with innocent people. They believe that they've killed infidels, and will be going to heaven. For those here in the real world, we call that Islamic Terrorism.
Even sects that are not sunnis...muslims consider them kaffirs so they blow the poor chaps up