John Owen on Mortification of Sin (1)

Bill Boekestein
In 1656 Puritan Pastor John Owen felt concerned that professing Christians were too “at peace in the world” (vii). He also believed that much of the teaching against sin in his day produced “superstition, self-righteousness and anxiety of conscience” in the hearers (viii). So, Owen wrote a little book called The Mortification (or “Putting to Death”) of Sin in Believers based on the second half of Romans 8:13. “For if you live according to the flesh you will die; but if by the Spirit you put to death the deeds of the body, you will live.” 
This verse outlines the duty of all believers, those who are “not in the flesh but in the Spirit” (v. 9). God encourages believers in their fight against sin. If we properly fight against sin we shall live. The means of mortification results in abundant life. But lest we become confident in our own strength we must know this, “It is a work of the Spirit, and it is by Him alone that we are to experience victory” (3). The Spirit empowers us to fight against indwelling sin in the same way that Christ crucified our former way of life in the cross (Rom. 6:6). As we put to death our sinful nature, our joy, comfort, and vigor increasingly come to life.
Principles of Mortification
Mortification is the duty of all believers (Col. 3:5; 2)
For six reasons, every believer must “Always being killing sin or it will be killing you” (5). First, believers will only be perfected in glory (Phil 3:12). We can only rest when sin is dead. Second, sin always works to produce bad fruit. “He that stands still and allows his enemies to exert double blows upon him without resistance will undoubtedly be conquered in the end” (7). Third, unchallenged sin becomes stronger and more deceitful. “Sin, if not continually mortified, will bring forth great, cursed, scandalous, and soul-destroying sins (Gal 5:19-20)” (Page Number??) Fourth, God gives us the Holy Spirit and our new nature to oppose sin and lust (Gal. 5:17; 2 Pet. 1:4). We must not neglect his gifts. Fifth, believers grow weaker toward God as sin strengthens in them. Unexercised grace will languish. Sixth, our spiritual growth is our daily duty (2 Pet. 3:18). “He who does not kill sin along the way is making no progress in his [Godward] journey” (10).
Those who do not put sin to death do themselves and others great harm. They promote a form of godliness that has no power to acquire eternal life.
Mortification Is by the Spirit
Any merely outward attempt to kill sin—taking vows, imposing strict rules on our bodies (Col. 2:23), adhering to religious duties—will fail. If God has not promised to work through these means they are powerless. If we put confidence in our efforts, even in our prayers, self-discipline, and promises, we sidestep the power of the gospel. 
Mortification is accomplished by the Spirit. The Holy Spirit gives us all the blessings we have in Christ including sanctification. God gives his Spirit to conquer our sin.
The Spirit mortifies our sin in a variety of ways. The Spirit causes us to abound in grace so that his fruit restricts the fruits of the flesh. The Spirit destroys our lusts. “He is the fire that burns up the very root of lust” (18). The Spirit causes believers to commune by faith with Christ in his death and sufferings. Without the Spirit’s help we would fight against sin but with no strength for the battle.
Even though the Spirit must put sin to death we are responsible for doing it with the Spirit’s help. 
Mortification Is of Great Benefit
To live a joyful spiritual life we must kill sin. Mortification of sin does not guarantees a pleasant life, as Psalm 88 makes plain. But without mortification our spirits cannot thrive. Failing to put sin to death will weaken the soul, and deprive it of its vigor. David complained of being unsound, feeble, and crushed by sins he let live (Ps. 38, 40, 51, etc.). “Sin untunes…the heart itself, by entangling its affections” (23). The soul that is entangled with worldly pursuits cannot be full of God. “Sin will also darken the soul, and deprive it of its comfort and peace” (24). Sin is like a cloud that intercepts “all the beams of God’s love…” (24). Unmortified hearts are like fields so overgrown with weeds that no good crop can grow.
Explanation of Mortification
What Mortification Is Not
First, mortification is not the utter destruction of sin in this life. We aim for, and seek the death of sin in this life but experience it only in the life to come (Phil. 3:12). Second, mortification is not the changing of some outward aspect of sin. It is possible to exchange one sinful habit for another that is less obvious or less dangerous. But, mortification is not mere substitution. Third, mortification is not the improvement of our natural constitution. Even without a new birth someone might subdue the outward signs of depravity. But superficial change does not get to sin’s root. Fourth, mortification is not the diversion of sin. An old man might lust less than he used to. But “he that changes pride for worldliness, or sensuality for legalism” is not killing sin (29). Fifth, mortification is not the occasional victory over sin. Sometimes when we commit a great sin we scare ourselves into not committing it again. Or, when greatly travailed we resolve to stop sinning to free ourselves of sin’s weight. In both cases sin is not mortified but dormant.
What Mortification Is
First, mortification is a habitual weakening of the lust. A lust is a “depraved habit or inclination” that “darkens the mind, extinguishes convictions,” and “dethrones reason” (33). In mortification we weaken sin’s habit so it fights less violently. We must be “crucifying the flesh with its passions and desires” (Gal. 5:24). Second, mortification is a constant fight and contention against sin. We need to identify the enemy against which we must fight “We cannot go forward unless we recognize the plague of our own hearts” (36). “We need to be intimately acquainted with the ways, wiles, methods, advantages, and occasions which give lust its success” (37). We need to daily attack our lusts even when we think they are dead. Third, mortification is a degree of success in the battle. As the spirit gains strength against the flesh we will begin to experience the victory of faith. As sin dies the believer will know greater peace of conscience and be bolstered by greater hope.
Rules of Mortification
Only Believers Can Mortify Sin
Only those who are raised with Christ can put to death earthly desires. A man who tries to kill sin without being converted is like a man who tries to build a house without a foundation. “There is no death of sin without the death of Christ” (41). “A servant who is directed to pay a bill must first collect the money at the bank” (41). Likewise, before we fight sin we must receive, in the Spirit, the power for mortification.
In fact, seeking mortification without regeneration is risky for several reasons. First, the mind and soul are diverted from that which is most important. Those who feel sin’s weight need to sense their need of Christ and believe the gospel. But in their impossible fight against sin they are distracted from seeing Christ as Savior. Second, the effort can bring a false peace of conscience. If a person can remove the symptoms of sin they can be tricked to believe they are cured. Third, when an unconverted person fails to mortify sin over a long period of time he might despair over ever defeating sin.
A person who fights against sin without believing in Jesus is actually practicing self-justification not Christianity. 
The Only Goal Must be Universal Mortification
“He who truly and thoroughly seeks to mortify any disquieting lust, must be equally diligent in all parts of obedience” (53). We make a mistake if we think we can only fight against the few sins that trouble our conscience. In fact, it is impossible to fight one sin without wholeheartedly drawing near to God. We only truly fight sin when we love Christ because he went to the cross, and hate all sins that sent them there. It is true that sometimes particular sins trouble us more than others. But these more weighty sins are often tokens of our more general negligence. They can awaken us to a more thorough change of heart and walk. 
*All page numbers refer to the "Puritan Paperback' edition.
Bill Boekestein