“You shall not make for yourself an idol in the form of anything in heaven above or on the earth beneath or in the waters below. You shall not bow down to them or worship them; for I, the LORD your God, am a jealous God, punishing the children for the sin of the fathers to the third and fourth generation of those who hate me, but showing love to a thousand generations of those who love me and keep my commandments. (Ex 20:4-6)
“Do not worship any other god, for the LORD, whose names in Jealous, is a jealous God.” (Ex 34:14)
“What does this mean? We usually think of jealousy as spiteful envy, but how could such an attitude be worthy of God? The answer is that there is more than one kind of jealousy. Of course, jealousy can be sinful, and with us, it usually is. The Oxford English Dictionary defines the word ‘jealous’ as ‘afraid, suspicious, or resentful of rivalry in love.’ This is the way we tend to be: resentful of rivalry. But the primary definition of the word is ‘fiercely protective’. And although God is neither suspicious nor resentful, he certainly is protective, especially when it comes to his relationship with his people. There is nothing God guards more jealously than his love for us and our love for him in the covenant.
According to J.I.Packer, ‘God’s jealousy is not a compund of frustration, envy, and spite, as human jealousy so often is, but appears instead as a praiseworthy zeal to preserve something supremely precious.’ When God told Moses that his name is Jealous, ‘He meant that He demands from those whom he has loved and redeemed utter and absolute loyalty, and will vindicate His claim by stern action against them if they betray His love by unfaithfulness.’ “
P.G.Ryken, Exodus: Saved for God’s Glory (Wheaton: Crossway, 2005), 1054-5.