Why should I fear God?
If we have learned anything from this time of protracted legal wrangling, it is that words are very important. The importance of words, however, lies not only in their definition, but also the context in which they are used. Fear is often discussed in God's Word. In some places fear is condemned, yet elsewhere it is encouraged. The difference in these cases is the original meaning and context.
You correctly state that we should fear God (Deuteronomy 6:13). Godly fear, though, may be better understood as profound reverence. This reverence is our response to God's power (Joshua 4:23-24), goodness (1 Samuel 12:24), judgment (Revelation 14:7), and forgiveness (Psalm 130:4). Godly fear is also constructive, leading to wisdom (Proverbs 1:7), purity (Psalm 19:9), and satisfaction (Proverbs 14:27).
At other times fear implies dread, dismay or anxiety. This fear results from, among other things, disobedience (Genesis 3:10), suspicion (Acts 9:26), or even death (Hebrews 2:15). This type of fear is destructive, leading to demoralization (1 Samuel 13:5-8) and paralysis (Matthew 28:4).
Whether we admit it or not, we are born with a knowledge and fear of God (Romans 2:14-15). The difference is Jesus. If you choose to follow Jesus, your fear of God is liberating, otherwise it is debilitating (Galatians 5:1). Those who deny Him dread what they will one day find out. Those who proclaim Him revere what they already know. The best definition of the fear of God may be "love on its knees."