I've often told my congregation that the opposite of faith, at least in the active sense, is not unbelief but fear. Fear is the electromagnetic pulse that disables faith. How many times in the Bible is a divine encounter or a mission assignment prefaced by the encouragement, "do not be afraid?" 65, at least! The faith-stifling affects of fear can't be minimized and should not be ignored.
Fear is the Devil's calling card, his MO. It is his means of controlling the herd and driving it to the slaughterhouse. If the Devil can induce fear in people, he's got them. Like a venomous spider's strike immobilizes prey so it can be eaten at a more convenient time, so the apprehension and terror the Devil inspires allows him to throw his victims in his satchel at his leisure. Though it's completely speculative, I've always wondered whether or not he said something to Adam and Eve to make them hide from God in the bushes.
Fear of punishment, fear of death, fear of loss or failure--the Devil has game at any level and with any kind of fear. I cannot prove it factually (other than in Job's case), but fear, even secretly held in the breast, seems to be a harbinger of bad things to come. I've known people that wear their fear as a badge of honor, as if it proves they care. It only proves that they scare. Fear will not deliver us from any unfortunate end, but it sure seems able to deliver us to those ends.
Faith on the other hand, portends good things to those that possess it. Faith in God can move a mountain or calm the storm at sea. Faith receives healing, welcomes the promise of God, and moves the faithful to act. Nothing is impossible for one who has faith! Fear clamps chains upon the unbelieving, whereas faith frees the soul to lay hold of God with a grip that holds even through the passage of death.
The truth is that if we have laid hold of God through faith, we have nothing to fear at all, not even fear itself.