Terrorist groups like Hammas and Hizbollah have one objective; to wipe Israel off the face of the earth.
Other groups, like Al Quaida, it's been alleged, will not be satisfied until the ENTIRE WORLD converts to Islam, and those who do not are destroyed.
You cannot reason with terrorists because they are Fanatics with unattainable goals.
I would tend to think, also that anyone who volunteers to be "Martyrs" is not going to start suddenly thinking rationally, and caring about innocents. To these people, unless you are a muslim, you are an enemy.
Of course, this is not the case with mainstream Islam. Like any religion, Islam has it's share of extremists.