for you shall worship no other god,
for the LORD, whose name is Jealous,
is a jealous God
Exodus 34:14 ESV
After the great exodus from Egypt by many signs and wonders from the hand of God, the LORD led His redeemed people into the wilderness, and within that wilderness, He made His covenant with them, giving them His law. Moses brought the people to Mount Sinai and had the people consecrate themselves at the foot of the mountain. On the third day, God descended upon the mountain, shrouding its top in smoke and fire, with lightening and great rolls of thunder and the blast of a trumpet. As the people of Israel stood in awe of their God, He spoke His law to them, saying:
I am the LORD your God, who brought you ought of the land of Egypt, out of the house of slavery.
You shall have no other gods before me.
You shall not make for yourself a carved image, or any likeness of anything that is in heaven above, or that is in the earth beneath, or that is in the water under the earth. You shall not bow down to them or serve them, for I the LORD your God am a jealous God, visiting iniquity of the fathers on the children to the third and fourth generation of those who hate me, but showing steadfast love to thousands of those who love me and keep my commandments.Exodus 20:2-6
WHOSE NAME IS JEALOUS
The jealousy of God is easily ranked among the most neglected of God’s attributes, and the reasoning is likely similar to the hesitancy toward calling God wrathful: both wrath and jealousy seem to be beneath God. Like wrath, we often associate jealousy with recklessness, but jealousy also has the added stigma of selfishness. When we think of someone given over to jealousy, we tend to imagine a controlling lover who is irrationally fearful that his or her beloved will prove to be unfaithful. Yet such an example of jealousy stands prominently within our minds precisely because it is so extreme.
For, indeed, there is a reasonable and righteous jealousy. In fact, the biblical premise of marriage requires this righteous jealousy. This jealousy is, as Packer explained, the “zeal to protect a love relationship or to avenge it when broken.” In this sense, I am certainly jealous for my wife. My love for her produces within me a jealous zeal for defending and strengthening our marriage. I also possess a similar jealousy for my daughter. While all children are precious and valuable, as my own child, she holds a special place within my heart, making me passionate to care for her and to protect her.
God’s use of both marital and parental language to describe His relationship to us is not accidental. The imperfect and sin-scarred love that we have for those closest to us is only a taste of God’s love toward His people. While the love I have for my wife and daughter is flawed with much selfishness, God is the perfect Husband and Father to us; thus, His jealousy for us also has no measure of wickedness at all. In fact, because God is goodness, His jealousy for our love can only be good. His command for us to love Him with all our heart, soul, and might is not megalomania because what better object of our love should He point us toward? Who or what is greater than God! It is His great jealousy for our own good that requires Him to point us toward Himself as our highest good. Just as John Piper has said countless times, “God is most glorified in us when we are most satisfied in Him.” His jealousy for His own glory is the same as His jealousy for our good.
A NECESSARY BEING
Because God grounds the Second Commandment in His jealousy, we must first see God’s jealousy as a warning against idolatry. If He truly is the one true and living God, why would we give ourselves over to gods that are not gods, to idols that are worthless? Why would we ever desire to leave our fountain of life and blessing in favor of barren deserts?
Yet this is the heart of idolatry. It exchanges “the truth about God for a lie” and causes us to serve “the creature rather than the Creator” (Romans 1:25). Fundamentally, it worships what is not God as God and, therefore, can only give empty promises and false hopes and comforts.
Yet the sin of idolatry is magnified by God’s jealousy toward us. When Adam and Eve first ate the fruit of the tree of the knowledge of good and evil, the LORD had every right to slay them in their sin at that very moment. They rebelled against Him. They disbelieved the very Creator who had given them everything, even making them in His own image. This first act of idolatry deserved the full outpouring of the Almighty’s wrath. But He did not slay them where they stood. In fact, His judgment against them was actually applied to their tasks rather than themselves (childbearing for the woman and working the ground for man). Make no mistake, God promised death as a result of sin, and death came, both physically and spiritually. However, He still delivered grace in the midst of judgment, promising a Savior who would in the end crush sin, evil, and death (Genesis 3:15).
And throughout the Bible, God keeps acting this way. Although He flooded the entire earth, He preserved Noah and His family. Although He destroyed Sodom and Gomorrah, His angels pulled Lot away from the desolation. Although Israel worshiped the golden calf, the LORD heard the intercession of Moses. Although they rejected God as their king, He gave them David, one of the great forerunners to the Messiah. And ultimately, the LORD sent us Jesus to free His people from our slavery to sin and to graft the Gentiles into the commonwealth of Israel. And this was all God’s eternal plan to redeem His people, the body and bride of Christ. These were acts of His jealousy for us. Packer was right, therefore, to observe that God’s jealousy “is constantly presented as a motive to action, whether in wrath or mercy.”
Again, His jealousy magnifies our sinful idolatry because it reminds us that our sin is not against some impersonal force of the universe that we call “God”; instead, when we sin, we sin against the very God who “so loved the world, that he gave his only Son, that whoever believes in him should not perish but have eternal life” (John 3:16). Since God often compares our idolatry to adultery, we should stand in wonder at His marvelous love and mercy toward us. Rather than divorcing Himself from us and damning us to suffer His eternal wrath within the lake of fire, He sent His only Son to save us by dying for us. Or consider the language of love used by God toward His idolatrous people through the prophet Hosea:
Therefore, behold, I will allure her, and bring her into the wilderness, and speak tenderly to her. And there I will give her her vineyards and make the Valley of Achor a door of hope. And there she shall answer as in the days of her youth, as at the time when she came out of the land of Egypt. And in that day, declares the LORD, you will call me ‘My Husband,’ and no longer will you call me ‘My Baal.’ For I will remove the names of the Baals from her mouth, and they shall be remembered by name no more. And I will make for them a covenant on that day with the beasts of the field, the birds of the heavens, and the creeping things of the ground. And I will abolish the bow, the sword, and war from the land, and I will make you lie down in safety. And I will betroth you to me forever. I will betroth you to me in righteousness and in justice, in steadfast love and in mercy. I will betroth you to me in faithfulness. And you shall know the LORD.Hosea 2:14-20
This is God’s jealousy, a jealousy that rightly views the hideousness of sin and bubbles over into wrath and justice against the unrepentant but mercy, grace, love, and faithfulness toward His people.
John Calvin warns us against such idolatry against God’s wonderful jealousy, saying:
Therefore, as the Lord always and in everything performs the duties of a faithful husband, so, on our side, he asks us to safeguard the love and chastity of marriage. In other words, we must not yield our souls to the devil and to fleshly appetite, which is rather like debauchery. For this reason, when he rebukes the Jews for their faithlessness, he complains that they have committed adultery and defied the law of marriage (Jer. 3:1-3; Hos. 2:1-7). Accordingly, like a good husband, the more faithful and trustworthy he is, the greater his anger if he sees his wife going after a lover. Thus the Lord who has truly wedded us confirms that he is wonderfully jealous whenever we despise marital chastity and defile ourselves with evil desires, and chiefly when we transfer his glory—which must be reserved above all for him alone—to another. Otherwise we sully his glory by our superstitious practice, for in doing this we not only violate the marriage vow, but we pollute our soul by our promiscuity.
In light of such goodness, we should always be jealous for our God, not polluting our souls by promiscuity, but instead loving Him supremely with all our heart, soul, and might and loving His image-bearers as we love ourselves.
 J. I. Packer, Knowing God, 170.
 Ibid. 168.
 John Calvin, Institutes of the Christian Religion: Calvin’s Own Essentials Edition, 130.