A Righteousness of the Heart - Putting off Lust and Pursuing Purity - Matthew 5:27-30
Introduction - A Righteousness of the Heart
In the Sermon on the Mount Jesus is teaching what it looks like to live as the people of God. What becomes abundantly clear is that God’s standard is much different than the standard of the scribes and Pharisees. In fact, Jesus says that the true people of God will have a righteousness that exceeds that of the scribes and Pharisees.
In Matthew 5:21-48 Jesus offers six examples contrasting the teaching of the scribes and Pharisees and the true law of God. What’s clear is that the righteousness of God is a righteousness of the heart and it goes far beyond the lines and parameters of the religious leaders. Further, we can never live up to God’s standard – but instead He gives those who are His new hearts – hearts that hunger and thirst for true righteousness.
In 5:27-30 Jesus gives the second of His six examples – this time contrasting the scribes and the Pharisees’ understanding and application of the seventh commandment with God’s true heart behind the command.
The Scope of the Command – What is adultery? (5:27-28)
- The command according to the scribes and Pharisees (v. 27) – The scribes and the Pharisees were right to teach and call for people to obey the seventh commandment. Scriptures are plain in their teaching about the sanctity of marriage and the seriousness of adultery (Proverbs 5:15-23; 6:32; Hebrews 13:4). But while they held to the command, they missed the true heart behind it. In their system the law was simple – if someone stopped short of the actual sexual act of adultery, they had kept the law and were to be considered righteous in regard to the law. However, Jesus is going to show that their application of the law was far too simple.
- The command according to Jesus (v. 28) - While the religious leaders were concerned with outward behavior (don’t commit adultery), Jesus is making it clear that the real standard is a matter of the heart – have you committed adultery in your heart? It’s about more than not bringing someone into your bed, it’s about not bringing them into your mind with lustful intent. Your long lustful look comes from an adulterous heart.
- An unpopular truth – The world (and our own sinful flesh) insists that lust is natural, normal and not something to be worried about. However, Jesus (and the whole of Scripture) teaches that to lust after a person who is not one’s spouse is misuse the good gifts of God. God has given us the gifts of beauty, sexual attraction and sexual fulfillment to be enjoyed, but they are to be used His way – within the confines of marriage.
The Seriousness of the Command – How serious is adultery? (5:29-30)
- It can lead to hell – While the world says our lust is natural, normal and innocent, Jesus says something very different. Jesus tells us that those who remain in their sin will be punished eternally by God in a place called hell. This is the end for all people who refuse to repent of their sin and trust in Jesus for salvation. If we are content to live with sinful lust in our hearts it may be a sign that we are not truly born of God (Colossians 3:5-6).
- A word of hope – The work of Jesus – The reality is that according to God’s standard most all of us are murders and adulterers. But Jesus came to offer hope for sinful people like us. Now, as those who have been called out of darkness, we are to walk in the light (Ephesians 5:1-8).
The Fight Against the Sin – How do we avoid adultery? (5:29-30)
- A new relationship with sin - When we become children of God our sinful desires don’t disappear, but our relationship with sin does change. While we were once slaves of sin, now we are set free from the enslavement of sin and we are called to fight against the temptation to remain in our sin (Romans 6:1-4).
- Radical amputation – Jesus leaves no doubt about the seriousness of sin and we see that in the way he tells us to combat the temptation to lust. His command is for radical amputation. While the call to take out our eye or cut off our hand may be hyperbolic, the point is that we should do whatever it takes to keep ourselves from sin (1 Pt. 1:13-21).
- John MacArthur – Just as the adulterous heart plans to expose itself to lust-satisfying situations, the godly heart plans to avoid them whenever possible and to flee from them when unavoidable. Just as the adulterous heart panders to itself in advance, so the godly heart protects itself in advance.
- D. A. Carson – What does Jesus mean? Just this: we are to deal drastically with sin. We must not pamper it, flirt with it, enjoy nibbling a little of it around the edges. We are to hate it, crush it, dig it out.
Hope for sinners – Jesus died so you can be forgiven of your sins – including lust and adultery (1 John 2:1-2; 1 John 1:8-9; Romans 6:1-4).
 John MacArthur, The MacArthur New Testament Commentary, Matthew 1-7, Moody Publishers, 1985, pg. 304
 D.A. Carson, Jesus’s Sermon on the Mount and His Confrontation of the World, A Study of Matthew 5-7, Baker Books, 1987, 2018, pg. 56.