Jealousy: First how do we describe jealousy? Merriam-Webster defines it as being intolerant of rivalry or unfaithfulness. Lets make a comparison of the word and in an unrighteous fashion as in jealousy being a "sin" and in a righteous sense as in "God is a jealous God".
The former description might include examples such as coveting your neighbor's 50" Plasma TV, feeling envy while listening to a friend's wonderful vacation stories, or perhaps wasting time pining over someone who is already in a committed relationship. Conversely the latter could be things such as a person desiring their spouse and children in their lives, items that they worked hard to acquire and now want to protect, and a desire for the credit of work done.
It is a sin to be jealous of something that someone else possesses, however it is righteous to desire that which is yours to begin with. In relationships for instance, it is necessary to desire the other person within the capacity of that relationship. Lets look at a related word, covet. It is a sin to covet another man's wife, however is it a sin to covet your own spouse? What is the meaning of the word? At what point does a fleeting thought of desire become "coveting"? Would thinking about the beauty of that person be OK or a sin? Would thinking about wanting to have that person as yours be a sin? Is this where we draw the line? Would making plans to obtain that person for your own be a sin? Would following through with the plans and putting them into action be wrong? I feel that desire in which the mind is thinking about someone/thing many times and even starting plans to make that person/item yours is coveting. He who has sinned in his heart... and all that.
However, desiring what is already yours, can you sin in coveting your own wife? I believe that this is actually mandatory in building healthy relationships. If you do not make plans to keep what is already yours then you will generally lose it. If you do not show the proper respect, love and affection for your spouse then you will fall into a "parallel marriage", (living separate lives without an actual breakup) or worse, divorce and separation. Coveting your own is needed in order to protect what is your own.
This is the difference between God's jealousy and man's jealously. Its really a question between jealously over what is yours already and what is not yours.
God is jealous because he is protecting what is already his creation. It is a sin to be jealous over what is not yours because you are failing to "put off the natural man" and you are failing to rise above your baser instincts, to become better then who you were. Protection of what is yours is needed, but taking what is not is wrong.
