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.
Spirit Empowered Killing
At this point we need to be very careful that we do not fall into an error of legalistic works-based performance where mortification becomes a sheer act of the will without the transforming help of the Holy Spirit. The fourth question we must ask about mortification manifests itself in the role we play along with the role of the Holy Spirit in killing sin. Paul says that we are to kill sin “by the Spirit”.
This work of killing sin is both monergistic and synergistic. By monergistic, we mean that the Holy Spirit alone does the work of killing sin. At the end of the day, all the credit for spiritual transformation or growth in grace comes from the sovereign Spirit of God. He alone produces the spiritual fruit and causes the growth. John Owen again says this about the Holy Spirit: “He is the fire which burns up the very root of lust.” Again, Owen also gives this sober reminder: “Mortification from a self-strength, carried on by ways of self-invention, unto the end of a self-righteousness, is the soul and substance of all false religion in the world.” By all means, we must implore the help of the great Helper Himself and constantly ask Him to come to our rescue in this grueling battle to kill sin.
But we are also called to be active in this process of killing sin. It is synergistic in that we also participate and cooperate with the Spirit in mortification. If we look closely at this passage, it does not say that the Holy Spirit will put to death the deeds of the body, but that we are responsible for putting them to death. We do this by the power of the Holy Spirit in our lives. John Owen gives a compelling case for this by saying, “The Holy Ghost works in us and upon us, as we are fit to be wrought in and upon; that is, so as to preserve our own liberty and free obedience. He works upon our understandings, wills, consciences, and affections, agreeably to their own natures: he works in us and with us, not against us or without us.” In other words, the Holy Spirit works with our regenerated hearts and compels us to obey. But He does not obey for us. He works in us, but not without us. We are still morally responsible agents who must take seriously the command to kill sin. When sin has been killed and true transformation occurs in our growth in godliness, in humility we look to the Spirit who has wrought this work in us and granted us the grace to obey. He alone deserves the credit for this, but we are still responsible for our part in this process.
Through the sanctifying power of the Holy Spirit, He grants us the grace to personally take responsibility to kill the deeds of the body. If we do not take an active part in this process of mortification, we can fall prey to the error mentioned in Chapter 7 about quietism. We will passively “let go and let God” and not see that the ruthless nature of killing involves active participation on our part to fight the good fight and kill sin. Jerry Bridges comments on his own personal experience with this type of thinking: “I misconstrued dependence on the Holy Spirit to mean I was to make no effort, that I had no responsibility. I mistakenly thought if I turned it all over to the Lord, He would make my choices for me and would choose obedience over disobedience.” Bishop Ryle again reminds us with these words: “He that pretends to condemn ‘fighting’ and teaches that we ought to sit still and ‘yield ourselves to God’, appears to me to misunderstand his Bible, and to make a great mistake”.
Autotomy is a scientific term which describes the act of self-amputation whereby a lizard severs its own appendages as a self-defense mechanism to evade the clutches of an oncoming predator. The amazing thing about this phenomenon is that the appendage may actually regenerate itself and grow back. For example, geckos and salamanders will shed part of their tail structure when captured in an attempt to escape. In a spiritual sense, we as believers are called to perform autotomy on our sin. We must amputate or kill the deeds of the flesh whenever we fear being captured by its devious grasp. In similar fashion to the regeneration of the gecko’s tail, our sin will always come back in full force. We will never fully kill sin in this life, but we can be persistent, brutal, and ruthless in this pursuit of mortification.
Remember Jesus’ words in Mark 9:43 about cutting off your hand if it causes you to sin. Many times we focus so much on the hyperbole of Jesus’ statement and try to over explain what it does not mean, that we fail to see what these powerful words actually do mean. Sin is a ruthless enemy that never sleeps, constantly attacks us, manipulates us with deception, and if not weakened and eventually killed, will lead a person straight into eternal destruction. Hear the words of Jesus again and instead of trying to explain away the outlandish demands of our Lord, receive them in the shocking manner in which they were originally meant to be received. We were meant to stand up in shock at the exaggeration of autotomy because the stakes are so high. Jesus said in Mark 9:34: “And if your hand causes you to sin, cut it off. It is better for you to enter life crippled than with two hands to go to hell, to the unquenchable fire.”
The ultimate destination for one who is entrenched in unrepentant, habitual, and persistent sin is the lake of unquenchable fire. There is no time to trifle with the allurements and amusements that sin has to offer when our eternal destinies are on the line. As regenerated and justified believers, we hear these words not as threatening demands of condemnation from a Judge, but as warnings from a heavenly Father who loves us too much to allow us to stay in a state of lackadaisical apathy when it comes to killing sin. We must be killing sin, or it will be killing us.
 John Owen, The Mortification of Sin, (Ross-shire, Scotland: Christian Heritage, 2002), 47
 Sinclair Ferguson, John Owen on the Christian Life, (Carlisle, Pennsylvania: Banner of Truth Trust, 1987),
 Jerry Bridges, The Pursuit of Holiness, (Colorado Springs, CO: Navpress, 1996), 79
 J.C. Ryle, Holiness, (England: Evangelical Press, reprinted 2001), 53