Cleanness and uncleanness, with respect to sin and guilt, are ultimately matters of the heart. Outward acts of sin that we commit against other people are truly violations of God’s law, and the Lord condemns them. However, the sinful words we speak and deeds that we do are but the fruits of inward sin. Transgression is not simply an outward matter but a matter of the desires of our hearts and minds. Jesus tells us as much in Matthew 15:10–20, and His exposition of the law in the Sermon on the Mount demonstrates that the commandments deal also with inward manifestations of sin (5:21–30).
This insight into sin’s being a matter of the heart goes all the way back to the Ten Commandments. The final commandment, in fact, deals specifically with our hearts and our desires in outlawing the sin of coveting. Covetousness is a sin of desire; it originates in our heart as we desire something that is not rightfully ours. Coveting is not synonymous with desire in itself. It is possible to desire lawfully something that we do not have; for example, Paul tells Timothy that men who desire the office of overseer or elder desire a good thing (1 Tim. 3:1). Covetousness is a grasping desire, a longing to possess what belongs to someone else. Desire for the office of overseer becomes covetousness, for instance, when we want to maneuver our way into removing one elder so that we can take his place. A good desire to get married becomes covetous when we lust after our neighbor’s wife and hope to take her as our own. A perfectly legitimate desire for a nice home or job becomes covetousness when we envy our neighbor who has such things and wish that he would lose them.
As Christians, we must put to death the covetous desires in our hearts. We must also be wise to the ways that our culture seeks to inculcate covetousness within us. Marketing campaigns are often crafted with the intent of fanning desires in our hearts for things that we should not have. Every election season, politicians stoke the fires of class envy, encouraging some groups of voters to see as enemies those who have privileges and possessions that said voters lack. Let us not fall into the trap of covetousness because of cultural pressure.
The Ten Commandments begin with heart desires—that we put God before all else—and end with heart desires—that we not covet our neighbor’s goods. May we apply God’s law to our hearts and seek the will of Christ that we may not sin against Him (Ps. 119:11).