Fear is good, of course. If it weren't for fear I wouldn't be writing this and you wouldn't be reading it because our ancestors would have been killed by snakes, tigers, or the people next door. Humans would not have stayed around long enough to invent Your Intertubes, smart bombs, KY Sensual Evening Wash, or any of the other things that make America great.
However, evolution has put fear on an overly sensitive trigger. For a small band of hunter gatherers on the edge of the Savannah, it's better to be unnecessarily scared 100 times than not scared when you should have been even once. There's very little cost to steering clear of a place, ducking and covering, or running. You can always gather your roots and berries later or someplace else, scavenge the next carcass, or go after the next herd of wildebeest. Also, it's very unlikely that fellow members of the band would give you false warnings -- what motive would they have? There was little hierarchy and nothing to steal.
Notice that evolution has made it possible for us to be equally afraid of what we observe with our own senses -- something that looks like a snake, or a dark forest -- and of what our fellows tell us, which is true of every social and flocking animal from chimpanzees to field mice that have alarm cries. So, unfortunately, in the very hierarchical, complex societies in which we live today, with immense stores of capital and institutionalized social power, there is plenty of motivation and opportunity for people who are in a position to do so to use fear to manipulate others.
There is along tradition of this in the United States beginning, of course, with our puritan preachers, the first leaders of the seminal English settler culture who specialized in terrifying the townspeople with horrific visions of hell. In 1741, Jonathan Edwards of Enfield (now in Connecticut), preached one of the most famous of the early American sermons, in which he said:
O sinner! Consider the fearful danger you are in: it is a great furnace of wrath, a wide and bottomless pit, full of the fire of wrath, that you are held over in the hand of that God, whose wrath is provoked and incensed as much against you, as against many of the damned in hell. You hang by a slender thread, with the flames of divine wrath flashing about it, and ready every moment to singe it, and burn it asunder; and you have no interest in any Mediator, and nothing to lay hold of to save yourself, nothing to keep off the flames of wrath, nothing of your own, nothing that you ever have done, nothing that you can do, to induce God to spare you one moment.
Except, of course, for Rev. Edwards and his church.
God seems now to be hastily gathering in his elect in all parts of the land; and probably the greater part of adult persons that ever shall be saved, will be brought in now in a little time, and that it will be as it was on the great out-pouring of the Spirit upon the Jews in the apostles' days; the election will obtain, and the rest will be blinded.
Funny thing about that, it didn't happen. Anyway, here we are again. This time, God's wrath will be visited upon us if we don't give George W. Bush and Alberto Gonzales the power to listen to our telephone calls and read our e-mails; to send young people eternally to shoot and bomb Iraqis and meet their own deaths in the process; to use the institutions of the law to persecute their enemies and protect their friends; to relieve the wealthy of the burden of taxation and to leave the poor to their spiritually enobling fate. In Edward's sermon, Satan was explicitly named as the instrument of God's wrath. In George W. Bush's sermon, God's instrument is Muslim terrorists.
What is inexpressibly discouraging about all this is that the election of a Democratic majority in both houses of Congress changed nothing. Your Democratic legislators are terrified into submission by the mere threat that Mr. Bush will blame them for God's anger, if they don't give him everything he wants. There is no help for us.