In the best case scenario, fears are a way for the subconscious to tell us to stay away from a potentially dangerous thing that is beyond our control or comprehension. Unfortunately, fears have a way of growing on the conscious part of ourselves too (where they don't belong) and spreading like a plague.
Fear of dark, fear of unknown, fear of death are the most famous archetypes of fear. However, I would have to say that 'fear of God' is the deepest archetype of them all, because it includes all these and more. To quote Marianne Williamson: "Our deepest fear is that we are powerful beyond measure. It is our light not our darkness that most frightens us."
Why would we be afraid of God's power and Love within us? Because it casts away our small vision of the world and brings us closer to God. Should we be afraid of God? Absolutely not. One of the most basic choices we can make in life is the decision between living in fear and living in Love. Fear doesn't mix well with unconditional Love, so choose wisely.
I strongly suggest replacing fear of God with Love for God. What does fear of God have to offer? An illusion of safety at best, which makes you think you're smart for being afraid. A wise man is cautious and considerate, but not afraid. Cautiousness doesn't mix with fear either - fear narrows the scope of our vision, thus makes it even more likely that we won't notice the pit we're heading for.
All-embracing Love (and not all-consuming fear) is the primary characteristic of God.