What did Jesus say about lust?

Let one instance suffice out of the seven occasions in that discourse when our Lord said, “I say to you.” “Ye have heard that it was said of them of old time, Thou shalt not commit adultery: but I say to you, That whosoever looks on a woman to lust after her has committed adultery with her already in his heart” (Matt. 5:27-28). Where is there the setting aside of the law? Nay, He upheld it. The law was content to forbid the actual act, the Lord went further, and not only forbad the outward act, but the inward desire.

As to the two commandments He quoted, His teaching evidently is that God has respect not only to the overt act but also to the inward disposition of the heart. What is prohibited is not merely the act of murder or adultery but the hatred and the lust of which the act is the expression. Judged by this standard, who is going to stand before the holy demands of Sinai? The "righteousness" of the scribe and Pharisee utterly collapses. Yet in both cases, having exposed this fact, He added some further instruction.

Thus was the mind of God made clear. The indulgence of lust is incompatible with entering the kingdom of the heavens. The law forbade the act of adultery; the Lord condemns even the looking licentiously as adultery committed already in the heart. He insisted therefore on the most unsparing decision with all that gave occasion. Was it not better to pluck out the right eye or cut off the right hand, rather than the whole body be cast into hell? Here (as in all the chapters of the first Gospel before Matthew 13 where He begins as the Sower), it is not seeking sinners in sovereign grace, but saints, as He enjoins on the twelve in chap. 10. "Into whatsoever city or village ye enter, inquire who in it is worthy" (ver. 11). So the beginning of the Sermon on the Mount (Matt. 5) describes what spiritual characters suit the kingdom, as the end (Matt. 7) declares that none shall enter but he that does the will of His Father that is in the heavens. Not even prophesying or miraculous powers, were it casting out demons through the Lord's name, could be a passport to the workers of lawlessness. Practical obedience of His words alone should stand. The rock here is spiritual reality. His word was incomparably more withering to self-righteousness than the law of Moses.

Adultery in the heart

The Lord Jesus now explains that before God it is not just the accomplished act that is sin, but the looking with lust on a woman, for this is adultery in the heart. The word "adultery" shows that either the man or both are married. Nevertheless, no unmarried believer should think that these words of the Lord have nothing to say to him.

The Lord is not speaking here about accidental, unintentional looks which can hardly be avoided, but about the conscious covetous looking: "Whosoever looketh on a woman to lust after her..." The intentional look is therefore preceded by the sinful thought in the heart.

The more casual and free contact between the sexes, especially with the younger generation and the negative example of most of their peers of the world, can lead to carelessness and great dangers. God-fearing Job said: "I made a covenant with mine eyes; why then should I think upon a maid?" (Job 31: 1). However, there are also over-sensitive and over-anxious Christians whose consciences are heavily burdened by involuntary looks and thoughts. I would like to remind such of the well-known words of Martin Luther which he wrote on this verse: "I cannot prevent a bird flying over my head, but what I can prevent is it building a nest in my hair or biting off my nose."

"And if thy right eye offend thee"

How serious the Lord judged the lustful looks and thoughts to be becomes obvious from His next words: "And if thy right eye offend thee, pluck it out, and cast it from thee: for it is profitable for thee that one of thy members should perish, and not that thy whole body should be cast into hell" (v. 29). In the next verse He says nearly the same with regard to the right hand (cf. ch. 18: 8).

The Lord is not calling for self-mutilation or asceticism in these words. The Creator will never demand that His creature mutilate the body he has received from Himself. Even if someone plucked out both his eyes, the lust would still remain in his heart. Rather, the Lord here extends the teaching to the question of self-judgment. The mention of the right hand points to this.

But there is another thing besides violence: there is the corrupt element in the heart of man — the heart lusting for that which it has not. This is taken up in the next word of our Lord: "Ye have heard that it was said by them of old time, Thou shalt not commit adultery: but I say unto you, that whosoever looketh on a woman to lust after her, hath committed adultery with her already in his heart. And if thy right eye offend thee, pluck it out and cast it from thee … And if thy right hand offend thee, cut it off, and cast it from thee: for it is profitable for thee that one of thy members should perish, and not that thy whole body should be cast into hell" (vers. 27-30). That is, whatever in our walk, or in our ways, or in our service, whatever it might be that exposes a soul to the danger of yielding to these unholy feelings, should never be spared, but departed from at any cost. There must be the excision of everything that is hurtful to the soul; the members of the body, such as the eye desiring and the hand which would take, being used as showing the various ways in which the heart might be entangled. The cutting off of these members sets forth a heart thoroughly exercised in self-judgment; not prompted to excuse itself by saying that it had not actually committed the sin, but whatever exposed to it must be given up.

It has been urged by some that the Lord's words in verses 21, 27, 33, 43, "Ye have heard it said of them of old time… but l say to you, " give a warrant for discarding the Scriptures and substituting for them something up to date. It is a scandalous and immoral procedure. He was shifting the searchlight from the outward actions to the unseen inner nature. One reason for which the law was given was to check and curb the lusts and passions of man, to hold within bounds the evil acts of his fallen nature. This is shown in Paul's first letter to Timothy. "But we know that the law is good if a man use it lawfully: knowing this, that the law is not made for a righteous man, but for the lawless and disobedient, for the ungodly and sinners, for unholy and profane, for murderers of fathers and murderers of mothers, for man-slayers" etc. (chap. 1:9, 19). Thus had it been rightly interpreted, but the Lord went deeper and dealt with the hidden desires of the heart, with the nature that lies at the root of every transgression and from which all evil deeds spring, and declared that God required truth in the inward parts. David learned in his great repentance, that more terrible than his deeds was the nature that produced them, and the law taught Saul of Tarsus the same necessary lesson (Romans 7). This did not make void the law, it established its use as a searching, convicting power.

It is sometimes said that deliverance from sin is a matter of personal effort, and that evil habits can and should be overcome by one's own firm resolution and perseverance. But this advice overlooks the fact that although the wicked deed may be checked by will-power alone, the sinful desire fills the heart beforehand. And divine holiness uncovers the secret source of inward evil. In God's sight, the thought of foolishness is sin. Our Lord condemns alike the lustful look and the adulterous act (Matt. 5:28). The evil thought defiles the whole man, as well as the evil word and the evil act (Mark 7:21-23). We should habitually govern our words and our deeds, but who can govern the imagination of the heart which God beholds? If we are walking with God, we are with One Who knows our thoughts even before we recognise them ourselves. The holiness of God is very pure, infinitely above any human standard, and in order to act rightly with regard to that standard, we must attend to the words of scripture concerning the “sin which doth so easily beset us.”

Some of us were speaking about the Sermon on the Mount as found in Matthew 5-7. We noticed how the Lord puts His hand on the desires of the heart. It is not sufficient to have strength not to commit the sins of the flesh, but the desire of the heart, as the flesh works, must not be encouraged. Though shame would forbid the outward acts of the flesh, yet if carnal desires are cherished in any way, then the Lord looks upon that as gravely as if the act were committed.

It is not the first step that leads to a public fall. There must be the secret encouragement before things get to the point of open scandal. In the Sermon on the Mount it is “the PURE in heart” that will see God. It is well to be exercised about the thoughts of the heart, for if they are kept in captivity to the Lord actions will be right. Spurgeon said, “You cannot forbid unclean birds flying over your head, but you can hinder their making a nest in your hair.”