“And I saw another angel fly in the midst of heaven, having the everlasting gospel to preach unto them that dwell on the earth, and to every nation, and kindred, and tongue, and people, Saying with a loud voice, Fear God, and give glory to Him; for the hour of His judgment is come: and worship Him that made heaven, and earth, and the sea, and the fountains of waters.”
“Wherefore we receiving a kingdom which cannot be moved, let us have grace, whereby we may serve God acceptably with reverence and godly fear.”
We can read how Jacob respected his father and swore by this respect:
“And Jacob sware by the fear of his father Isaac.”
Because we respect God, we desire to obey God.
“Let us hear the conclusion of the whole matter: Fear God, and keep his commandments: for this is the whole duty of man.”
“The secret of the Lord is with them that fear him; and he will shew them his covenant.”
“There was a man in the land of Uz, whose name was Job; and that man was perfect and upright, and one that feared God, and eschewed evil.”
In speaking of a kingdom who did not obey God's commandments, Abraham said:
“...Surely the fear of God is not in this place; and they will slay me for my wife's sake.”
So the fear of God is the keeping of the Commandments that He setup trusting that they are for our best interests.
To fear God is trust Him and obey requests even when we do not understand why. Another example of this was with Abraham where God asked him to do the unthinkable, to kill his son. This seemed against logic and yet Abraham decided to obey. We read that this obedience demonstrated his trust.
“And he said, Lay not thine hand upon the lad, neither do thou any thing unto him: for now I know that thou fearest God, seeing thou hast not withheld thy son, thine only son from me.”
“The fear of the Lord is the beginning of wisdom: and the knowledge of the holy is understanding.”