Theland:
Al-Qu'ran, 6:151:
...take not life, which God has made sacred, except by way of justice and law: thus does He command you, that you may learn wisdom.
5:32
if any one slew a person - unless it be for murder or for spreading mischief in the land - it would be as if he slew the whole people: and if any one saved a life, it would as if he saved the life of the whole people.
So the Koran is really no more or less condoning of killing than the bible is. And it's just as ambiguous in places. Those terrorists aren't the mainstream in exactly the same way the Christian fundies aren't the mainstream of Christianity.
Thus 'banning islam' is not only totally overkill, but impractical and is far more likely to drive more people into the arms of terrorism than specifically targeting those who have committed atrocities is.
It never fails to astound me that people still believe in the C21 that individual members of whole religions or communities are are all implicit in the actions of each other. And that goes for Islamic fundies just as much as anyone else.