There are two kinds of fear. The American Heritage Dictionary defines fear as "a feeling of alarm or disquiet caused by the expectation of danger, pain, disaster, or the like; terror; dread; apprehension." And also defines fear as "extreme reverence or awe, as toward a supreme power."
It is this reverence or awe that God's Word teaches saints to have towards God. Hebrews 12:28 says that there is a godly fear with which we are supposed to serve God and thereby implies that there is an ungodly fear that is not acceptable in serving God.
Satan has always used this ungodly dread or terror to torment godly people. Those who have been born again should have no dread or terror of God unless they are planning to renounce their faith in Jesus as their Savior.
We have a covenant that guarantees us acceptance with God (Ephesians 1:6), as long as we hold fast to our profession of faith in the atoning blood of our Savior, Jesus Christ.
For an unbeliever, the fear of the Lord is a great deterrent from sin. For those of us who have received the grace of God, it is His goodness that causes us to fear him and depart from sin. His goodness is awesome!