What is the "fear" of God? The book of Proverbs, and several other places in the Bible, mention the "fear of the Lord".


  Proverbs 9:10 (ESV)
  The fear of the Lord is the beginning of wisdom, and the knowledge of the Holy One is insight.


In other contexts, such as when God spoke to Abraham, he said "fear not".


  Genesis 15:1 (ESV)
  After these things the word of the Lord came to Abram in a vision: “Fear not, Abram, I am your shield; your reward shall be very great.”


In yet other contexts, the "fear of the Lord" is praised as a great thing.


  Isaiah 33:6 (ESV)
  and he will be the stability of your times,
  abundance of salvation, wisdom, and knowledge;
  the fear of the Lord is Zion's treasure.


What is the difference in these context and in what sense are Christians supposed to "fear" the Lord?
Proverbs 9:10 and Isaiah 33:6 are referring to the fear of offending the Lord or sinning.

I believe in Genesis 15:1 God is telling Abraham that he does not need to have fear, because he did a good thing by rejecting the king of Sodom's reward in Genesis 14:21-24.

The Catholic Bible states it pretty well when it says, "Lastly, the gift of fear fills us with a sovereign respect for God, and makes us dread, above all things, to offend Him."

This is saying that we should have so much respect for God that we should fear ever offending him.  While the source is Catholic, I don't necessarily take it as a Catholic only stance.

Some say we should fear the Lord's wrath, but I believe the wrath alone should not be why we fear sinning.  It should also be out of love and respect for the Lord.