First off, God wiped out the world because of the deepness of Sin that man was in. THus, sin is associated with Lucifer. Oh, and the guy's name wasnt Jacob, it was Job. God did not kill Job family. If you read in the Bible, Satan came to God and basically asked permission to try Job, because he believed that Job wasnt as holy as God thought he was. So, God let Satan try Job. He didnt make Jacob worship him because every human being has the right to Freewill. Read Chapter 1 of Job, it explains it. Job is quoted for saying one of the most well known scriptures in the bible. Job 1 Chapter 21 reads, "And said, Naked came I out of my mother's womb, and naked shall I return thither: the Lord gave, and the Lord hath taken away; Blessed be the name of the Lord." (King James Version.) And the guy that you are talking about, his name was Abraham, and his son's name was Issac. God himself tested Abraham because he wanted to see how deep his faith was. Genesis chapter 22 explains the story. Verse 11 and 12 state, "and the angel of the Lord called unto him out of heaven, and said, Abraham, Abraham: and he said, Here am I. 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 has not withheld thy son, thine only son from me" (King James Version).
Secondly, the fear that you are using is being used in a different text then what is used in the bible. In the old testiment, fear is associated with "religion", while in the new testiment, it refers to those who are faithful towards God. Also, God is no respecter of person, therefore a sin is a sin. A person that has lied is just a guilty if not guilter than a person who has raped someone. The mindset of man has created the various degrees of sin, not God. However, there are sins that are specified in the Bible that are considered more blatant towards God.

But that should Help Mad Dog. If you need to know anything else, just get at me.

__________________
Grim