The Greek word translated as "looks" implies intent or special contemplation. The word underneath "lust" means "to set one's heart upon" or "to long for." Taken together, they make Jesus' instruction obvious.
Evidence from other portions of God's Word shows that it is not wrong to desire a husband or wife lawfully, but it is most definitely wrong when the one desired is legitimately beyond the reach of the admirer. How often does such admiration merge into a desire to possess and thus break the commandment? Considering the national statistics on divorce, this must happen frequently.
The Jews of Jesus' time perceived adultery as a kind of theft. This is not entirely wrong, but in this context, Jesus' emphasis is on moral purity: Ruin awaits those who are unchaste, even in thought.
Perhaps nowhere in Scripture is the inwardness of Christ's teaching as evident as with this commandment—inward in the sense that within is where sin begins and also where change must take place. It identifies where the problem resides. Christ carries impurity back beyond the lustful act to the first touch of the hands to the look of the eyes—and beyond these, to the first inception of desire. The Christian must "amputate" the desire so that the sin never becomes an act. We will remain pure and so will the object of our desire.
God gave us the wonderful gift of imagination, but if fed dirt by the eye, the imagination will be filthy. Sin begins with our allowing the imagination to dwell on what it should not. What feeds the imagination is so very important to moral purity and thinking and therefore to sin. Philippians 4:8 provides excellent insight:
Finally, brethren, whatever things are true, whatever things are noble, whatever things are just, whatever things are pure, whatever things are lovely, whatever things are of good report, if there is any virtue and if there is anything praiseworthy—meditate on these things.
The advice is clear: We must stop feeding our imagination dirt. We have to deal radically with sin! The purpose of this discipline is enrichment of life. The person who is condemned here is the one who deliberately uses his eyes and mind to awaken his lust so that desire is stimulated.
It is hard enough to avoid lusting after natural things, but this world deliberately designs many things to spark wrong desires in us. If certain books, pictures, magazines, places, activities, or people cause temptation, they must be avoided regardless of the cost. Avoiding sin is that important!
John W. Ritenbaugh
The Tenth Commandment
Christ's instruction in His Sermon on the Mount is exactly what He gave to His servant Moses for Israel. Both teach us that marriage is permanent, its ties so binding that they can be broken only by death—or something worse: physical infidelity, moral abandonment, or sustained abuse by either spouse, all of which Jesus encapsulates in the term porneia, translated as "sexual immorality."
The Pharisees tested our Lord on this point, but His response leaves no doubt on how binding the institution of marriage should be, a standard set from creation:
And He answered and said to them, "Have you not read that He who made them at the beginning 'made them male and female,' and said, 'For this reason a man shall leave his father and mother and be joined to his wife, and the two shall become one flesh'? So then, they are no longer two but one flesh. Therefore what God has joined together, let not man separate." (Matthew 19:4-6)
Because marriage is a creation of God, it possesses a sacredness that no man-devised institution can ever have. This world is trying to exchange the sanctity of marriage for its complete opposite, the profane, but this secular approach will never produce a healthy society.
The Sacredness of Marriage
Why Did Jesus Say to Pluck Out Our Eye If It Offends Us (Matthew 5:29-30)?
Christ does not intend for us to take this instruction literally. Jesus does not want sinners to become physically handicapped. Because sin begins in the mind, the eye, the hand, or the foot cannot sin of and by themselves. Even without these body parts, a person can still sin.
Our Savior often employs figures of speech in His preaching. Here, He is simply using parts of the body to elucidate an important principle—that a Christian should not tolerate sin in his life. Once a sin becomes apparent, we should take immediate steps to eliminate it from our lives. By using the striking example of amputation, Christ also illustrates that the process of overcoming sin may be as painful as losing an arm, a leg, or an eye. Ultimately, it is far better to give up a sinful pleasure than to lose out on salvation (Hebrews 11:23-26). The apostle Paul expands Jesus' instruction in Colossians 3:1-17.
Overcoming (Part 1): Self-Deception
The Formula for Overcoming
Elements of Motivation (Part 6)
He Who Overcomes
Other Forerunner Commentary entries containing Matthew 5:29:
1 John 3:20