Let's be clear about one thing. Apologists for this sort of terrorism like to point to the war in Iraq as a a trigger for which these people are seeking revenge. The bulk of the dead in Iraq were muslims killed my other muslims, Sunni v. shia.
The end game is not one of revenge, it is the complete slaughter of us unbelievers. That is what the extreme version of islam dictates. With this in mind I don't see any basis for discussion or negotiation. Islam has no place in secular Western society, but if muslims want to pray to a mythical god from 2,000 years ago then that is fine by me, as long as the do it in Islamabad, Mecca, Baghdad or whatever other hellhole they chose to live.