Reflecting on Jesus’ words here, people have sometimes thought, “If I am going to be flagged for adultery by lusting after someone, why not have some fun and go ahead with adultery, all at the same cost?”

But that was not Jesus’ point. Lust is a vice. Vices are evil tendencies and desires. They are wrong and must be combatted daily. Vices are sinful motives, and when we let them control our hearts and minds, they lead us to sin. And the sins they lead to cause greater harm than the vice itself.

So lust is a vice that can lead to the far more sinful act of adultery. Adultery is far worse because it has worse conse­quences. Thinking about having sex with someone may have a negative effect on the character of the one who is lusting. But any nonmarital sex affects the sinner and others deeply. It has the potential to break a marriage, or to make a future marriage begin with suspicion.

Not all sins are the same. Some have minor consequences; others have far greater consequences.

Jesus was hardly suggesting that since we have broken one law, we should feel free to break more. He was showing that the desire that leads to sin is itself sinful and needs to be addressed.