Iran is not a democracy, of any sort. It is run radical shiite clerics whose goal is to kill all "infidels" so that their messiah the "12th emam" can return. They believe that he cannot and will not return until they kill all of the infidels ("the earth is washed with the blood of the infidels" or some such thing). Stop and think about that. So it is up to them to "hasten" his return. We're standing in the way of their savior being able to return (in their minds) !!! This is what most people in the west don't understand. This is "why we fight" (a troop saying) at this point in history.
There are no true democracies in the middle east except for Lebanon (which is largely christian), but they are being terribly brutalized by Hezzbolah terrorists (which is linked to Iran).
There are radical groups here and there that subscribe to this particular brand of islam. Some are Sunni (which is what AlQueda is), some are Shiite (Iranian). You almost have to keep a score card to keep track of which side any given radical is on.
But the Iranian radicals in control of the gov't are a minority, but a powerful and brutal one. Hopefully the moderate iranians, who don't believe in the emam doctrine will rise up and overthrow the mullahs in charge. The mullahs feel threatened by a true democracy right next door to them. No, democracy isn't the end all and be all of all the worlds troubles, but it could erode the power and influence the mullah/terrorist have by giving people hope of not having to live under brutal terrorist regimes.