Radical groups only find traction when the people they are appealing to are faced with desperate circumstances.
Hitler after Versailles, the Palestinians and Israel, the Bolsheviks and the Tsar, those are the examples that readily come to mind.
Now that the Cold War is over, we're the last heavyweight around. When we staged our troops in Saudi Arabia for Operation Desert Storm, OBL and the boyz resolved to purge us from their homeland, the country of their religious shrine, Mecca. They believe we have desecrated their religious homeland for our material gain. There's really no point in debating the niceties of whether they're right or wrong, the simple fact is that the basis for their belief is there as long as we are.
So maybe it's time to try something different. Like getting the flock outta there.
If we don't like what they do after we leave, we've got the most powerful naval, air and amphibious forces in the history of man to monitor and intervene, should that ever be necessary.