The second thing that Jesus does in this passage is demonstrate the need for a new heart. Look at v. 28.

28 But I tell you, everyone who looks at a woman lustfully has already committed adultery with her in his heart.  

Now, this teaching is classically misunderstood, so I want to walk through it with you carefully.

First, “But I tell you.” Jesus speaks emphatically and sternly. He reminds them that HE IS the fulfillment of the law, and that HE IS the authority, not their own rabbinic tradition.

“But I tell you that “EVERYONE WHO LOOKS” … the Greek is VERY IMPORTANT here. A more literal translation would read like this: “But I tell you that everyone who engages in the process of continually looking.” Do you see the idea? The act of lusting that Jesus is talking about is not the inadvertent glance … the accidental glance. Rather, it is the purposeful … repeated … engaging looking.

It’s not lust to be attracted to someone or notice that they are good looking. It’s not lust to have a strong desire to have sex. It’s not lust to anticipate and be excited about sex in marriage. It’s not lust to experience sexual temptation.

You see my point. But it’s an important one. If we fail to know and understand this distinction that Jesus makes, our quest to be obedient is difficult. We can’t know if we’re winning if we don’t know the rules. On the one hand, we can find ourselves excusing sinful thoughts and actions as “natural.” On the other hand, we can end up being ashamed of having a sex drive. Both of these are tragic mistakes.

The verse continues.

28 But I tell you, everyone who looks at a woman lustfully has already committed adultery with her in his heart.   

It’s the last part of this verse that we often misunderstand. 

Jesus does not say, “Everyone who looks at a woman with lustful intent COMMITS ADULTERY.”  NO!  What he says is that the person who looks lustfully “HAS ALREADY COMMITTED ADULTERY WITH HER IN HIS HEART.”  

Why? Because it is the fallen heart that leads to lusting! It is our heart that is the problem. In the same way that no amount of not murdering a person won’t purify a heart that angers, no amount of “not sleeping with another person’s spouse” is going to make a lustful heart righteous. Our depravity is TOTAL.

So, what do we do?

Well, remember what Jesus is doing at large in this section. He’s demonstrating again and again through different laws and teachings that an external, law-keeping obedience is not true righteousness. We need a righteousness that only He can give us. It’s really great you don’t actually cheat on your spouse. But that won’t change your heart. Your heart, by definition, is a cheater.

But a new heart DOES something different. We’ll look at this in our next post.