Jesus deals with this topic of the mortification of sin in Matthew 5:29-30.

“And if your right eye makes you stumble, tear it out, and throw it from you; for it is better for you that one of the parts of your body perish, than for your whole body to be thrown into hell. 30 “And if your right hand makes you stumble, cut it off, and throw it from you; for it is better for you that one of the parts of your body perish, than for your whole body to go into hell.

Some do not identify this passage as one that deals with the mortification of sin, but D. Martyn Lloyd-Jones, in his book, Studies in the Sermon on the Mount insists that it does. And notice that it comes directly after verses 27-28, which deals with the sin of adultery; or more precisely, adultery in the heart. And we have previously spoke of it as the exceeding sinfulness of sin or sin as a disease or a corruption of the heart.

Thus, because sin always corrupts, and some sins do more than others, we must deal with it and try to get rid of it, no matter the cost or the pain. The right eye and the right hand, in verses 29-30, represent something of great value to us that causes us to sin; that is why it is the right eye and the right hand. But we must not take this passage literally; Jesus was not advocating self-mutilation. Sin is of the heart, not the body. We must deal with the heart and try to figure out how to mortify (or destroy) sin in the heart.

Here are seven points, by D. Martyn Lloyd-Jones (adapted to this blog) on how to deal with the corruption of sin in the heart.

1. Realize the nature of sin and its consequences. An inadequate view of sin is the chief cause of a lack of holiness. We must realize that sin has polluted our entire being.

2. Realize the importance of the soul and its destiny. If something is a harm to the soul, we must hate it. It is our enemy. Nothing must be allowed to come between you and your soul’s eternal destiny. The most important thing we have to do in this world is to prepare ourselves for eternity. It is better to be crippled in this life than to lose everything in the next life. Certainly, that was Jesus teaching in our passage (Matt. 5: 29-30).

3. We must hate sin within us and do all we can to destroy it all costs. We must train ourselves to hate sin. Know sin, read the biblical descriptions of it, analyze it, and thus grow to hate it.

4. The ideal is to have a clean and pure heart. We should not be simply satisfied to be free of certain actions, but to have a pure heart. For Jesus said, “Blessed are the pure in heart.”

5. Realize the great importance of the mortification of sin. We may better do that by meditating on the following verses: Romans 8:13 (mortify sin to live spiritually); 1 Corinthians 9:27 (bring the body into subjection); Romans 13:14 (make no provision for the flesh); I Corinthians 6:18 (flee immorality); Ephesians 5:18 (be filled with the Spirit); Psalm 119:11 (treasure the Word in your heart).

6. Never feed the flesh. Purpose not to read any material, listen to anything on the radio, or watch any TV or movies that have fleshly or sinful content. It will be like adding fuel to the flames of the flesh.

7. Regularly remind yourself of the price that had to be paid to deliver us from sin. Such love demands our holiness.