The most graphic image that Scripture uses for the killing of sin is crucifixion. The cross has rightly stood at the center of Christian theology throughout church history.
Crucifixion was so painful that a word was invented to describe it: excruciating, which literally means “out of the cross”. The Jewish historian Josephus said that to be crucified was to die a thousand deaths. The Roman historian Cicero said, “There is no fitting word that can possibly describe so horrible a deed” as crucifixion, and “the very word ‘cross’ should be far removed not only from the person of a Roman citizen, but from his thoughts, eyes, and his ears.”
With this background, we can begin to understand why it was so scandalous for Christians to serve a crucified King. But despite the scandal, Paul actually boasted in the cross and represented the life of a Christian as a crucified life, employing this graphic image as a metaphor for the believer’s relationship with sin. Paul’s words to the Galatians were especially poignant:
For through the law I died to the law, so that I might live to God. I have been crucified with Christ. It is no longer I who live, but Christ who lives in me. And the life I now live in the flesh I live by faith in the Son of God, who loved me and gave himself for me…And those who belong to Christ Jesus have crucified the flesh with its passions and desires…But far be it from me to boast except in the cross of our Lord Jesus Christ, by which the world has been crucified to me, and I to the world (Galatians 2:19–20, 5:24, 6:14).
What was it about crucifixion that led Paul to write this way, and what does it mean for us today?
The Cross and the Nature of Mortification
“Those who belong to Christ Jesus have crucified the flesh with its passions and desires,” writes Paul in Galatians 5:24. These words depict the nature of a believer’s break with sin in graphic, but insightful, terms. Sin’s death is like a crucifixion: slow, gradual, painful, and eventually final.
When a condemned criminal picked up his cross to carry it to the execution site, there was no turning back, no chance for reprieve, parole, or pardon. Crucifixion was a death sentence. But the death would be gradual, often taking not only hours, but days. When first nailed to the cross, the victim would struggle for survival, crying out in agony with all his might. But as he lost blood and strength, the struggle would lessen and his cries would grow faint.
Putting sin to death is a similar experience. There is a finality to the decisive break with sin to which our Lord calls us: “If anyone would come after me, let him deny himself and take up his cross and follow me” (Mark 8:34). Once we truly pick up our cross, having had our hearts changed by the grace of Christ to yield our lives to Him, there is no turning back. The die has been cast, the future has been determined: sin must be killed. Taking up the cross to follow Jesus means that sin has received a death sentence. But it doesn’t die all at once. No, putting sin to death is a slow process.
Mortification is also a painful process, and we must never allow ourselves to think that the pain associated with sanctification is a sign that something is wrong. Crucifixion is painful, and Scripture presents mortification as a kind of crucifixion. The pain cannot be separated from the process.
At first, our sinful flesh struggles against the Spirit, screaming in agony to be spared. But mortification gradually weakens the power of sinful desires in our hearts. In the words of Octavius Winslow, “Nail after nail must pierce our corruptions, until the entire body of sin, each member thus transfixed, is crucified and slain.”
The Cross and the Power of Mortification
The image of crucifixion provides a second and even more important insight about mortification. This truth is found in its connection to Christ’s crucifixion for us. In Galatians 2, Paul points to our crucifixion with Christ:
“I have been crucified with Christ. It is no longer I who live, but Christ who lives in me. And the life I now live in the flesh I live by faith in the Son of God, who loved me and gave himself for me” (Galatians 2:20).
It is significant that this precedes Paul’s later statements in this letter about crucifying the flesh and being crucified to the world (Galatians 5:24, 6:14).
The death of sin in the death of Christ—this connection reminds us that the power of mortification comes directly from Christ crucified for us. As John Owen said, “The death of Christ is the death of sin.” Only by virtue of His death to sin as our representative do we receive the power to renounce sin in our lives.
This is also the teaching of Paul in Romans 6, where he says that “our old self was crucified with [Christ]…so that we would no longer be enslaved to sin” (v 6). This is part of Paul’s argument for why it is morally incongruous for a believer to continue to live in sin. Christ was crucified for sin (not His, but ours). In His death, “he died to sin, once for all” (v 10), meaning that He died to the judicial power and authority of sin. Since we died with Him, sin has lost its power over us. “So,” Paul says, “you also must consider yourselves dead to sin and alive to God in Christ Jesus. Let not sin therefore reign in your mortal body, to make you obey its passions” (vv. 11–12).
This means that the power we need for crucifying sin comes from the cross, where Christ was crucified. It is only through virtue of His death to sin that you and I can put sin to death in our lives. The only way you can kill sin is through the power of the Spirit applying the death of Christ to your heart and life.
“Let us slay sin, for Christ was slain.”
Christ’s effectual sin-canceling work of the cross is therefore the only power that will enable us to kill sin in our own lives. And this is one of the purposes for which He died. As Peter says, “He himself bore our sins in his body on the tree, that we might die to sin and live to righteousness. By his wounds you have been healed” (1 Peter 2:24).
As the great nineteenth-century preacher Charles Spurgeon, in one of his characteristically Christ-centered sermons, declared:
The best preaching is:
“We preach Christ crucified.” The best living is, “We are crucified with Christ.” The best man is a crucified man…The more we live beholding our Lord’s unutterable griefs, and understanding how he has fully put away our sin, the more holiness shall we produce. The more we dwell where the cries of Calvary can be heard, where we can view heaven, and earth, and hell, all moved by his wondrous passion—the more noble will our lives become. Nothing puts life into men like a dying Savior. Get you close to Christ, and carry the remembrance of him about you from day to day, and you will do right royal deeds. Come, let us slay sin, for Christ was slain. Come, let us bury all our pride, for Christ was buried. Come, let us rise to newness of life, for Christ has risen.
The Cross and the Means of Mortification
We have been discussing the objective power of the cross of Christ to put our sins to death. This objective power is real and effectual, regardless of our feelings about it at any given point. But there is also a subjective element involved: we must exercise faith in Christ and His cross in order to enjoy the fruits of His victory over sin in our lives. As Paul goes on to say, “Far be it from me to boast except in the cross of our Lord Jesus Christ, by which the world has been crucified to me, and I to the world” (Galatians 6:14).
The cross not only shows us (1) the nature of mortification (a slow, gradual, painful death), and (2) the power of mortification (crucifixion with Christ). It also shows us (3) the means of mortification. In order to kill sin, we must exercise both faith and love. We exercise these graces by fixing our minds on and filling our affections with the cross of Christ.
How to Do It
But how do we practically set our minds on and fill our affections with the cross? How do we exercise faith and love toward Christ crucified for us? It is not done with a crucifix or some other visual aid. This is not the method proposed in Scripture. No, Paul tells us how Christ is portrayed as crucified: “It was before your eyes [that is, through preaching] that Jesus Christ was publicly portrayed as crucified. Let me ask you only this: Did you receive the Spirit by works of the law or by hearing with faith?” (Galatians 3:1b–2).
The great object of our faith and love is Christ, as portrayed in the gospel. Only as we gaze on the glory of the Lord in the gospel are we transformed by the Spirit (2nd Corinthians 3:18). We do this as we:
- Consider the purpose of Christ’s death for us with an expectation of help from Him.
- Consider how our Savior died to destroy the works of the Devil, to redeem us from lawlessness, and to cleanse and sanctify us through his blood.
- Meditate on the mercy and compassion of Christ, the mighty Maker who died in your place.
- Remember that your ransom was purchased at the price of His precious blood.
- Consider the cost of the gifts you have received through the cross—wisdom, righteousness, holiness, sonship, redemption, and future resurrection to glory forever.
- Reflect on the salvation and safety that your Brother, Captain, and King has secured for you.
- Realize that God is more satisfied with Jesus’ obedience than He was grieved by your sins.
- Ponder the pain and the shame of the scourging and scoffing, the spitting and mocking, the crown of thorns and the nails in His hands, and all the cruel wounds He received on your behalf.
- Understand that you are not only acquitted, but accepted as fully righteous in God’s sight, perfect in the eyes of the law, because the full measure of divine wrath was poured out on Jesus for you, and His obedience has been counted as yours.
- Allow our hearts to be filled with the glories of His triumph over Satan, sin, and death.
- Allow our affections to be captured anew by the self-sacrificing love of the Lord and Lover of our souls; then we will discover that the stranglehold of sin on our hearts has grown weaker, that sin is less alluring, and that our fallen desires have been displaced by desires for God, His glory, and His grace.
My sin, oh, the bliss of this glorious thought!
My sin, not in part but the whole,
Is nailed to the cross, and I bear it no more,
Praise the Lord, praise the Lord, O my soul!
When you are fighting sin, fill your mind with these truths. Say to the Lord, “Jesus, you died to free me from sin, to put my sinful passions and desires to death, to change me and restore me in Your glorious image. Thank you for Your undying love! Now, cleanse me with Your blood. Strengthen me with Your power. Uphold me by Your grace. Help me, Lord!” This posture of dependent faith and zealous love toward the Savior, who was slain for us, is lethal to sin.
 Cicero, quoted in Gordon D. Fee, Paul’s Letter to the Philippians (Eerdmans, 1995), 217–218.
 Octavius Winslow, No Condemnation in Christ Jesus (The Banner of Truth Trust, 1991), 151.
 John Owen, The Holy Spirit: Abridged and Made Easy to Read by R. J. K. Law (The Banner of Truth Trust, 1998), 175.
 C. H. Spurgeon, “To Lovers of Jesus – An Example” in The Metropolitan Tabernacle Pulpit (Pilgrim Publications, 1977 reprint) Sermon #1834.
 Horatio Spafford, “It Is Well with My Soul,” 1873.