Central to the practice of mortification is the believer’s union with Christ Jesus. In Romans 6:1–13, Paul shows the relationship of union with Christ to mortification. In Romans 6, the apostle is answering the objection that justification promotes sin. He teaches that the work of Christ on the cross, which is the basis for justification, is also the basis of sanctification.
Paul bases his argument on the believer’s union with Christ in His death and resurrection. He says, “For if we have become united with Him in the likeness of His death, certainly we shall be also in the likeness of His resurrection” (Rom. 6:5 nasb).
The Bible sets forth this union under two heads: the believer is in union with Christ by covenant and by conversion. First, the believer is in union with Christ by covenant. In 1 Cor. 15:21–22, Paul establishes that all mankind was brought into sin and condemnation because it was in covenant with Adam. Similarly, all the elect are saved because they are in union with the Lord Jesus Christ.
When Christ came to earth He obeyed the law of God perfectly and offered His sinless life as a sacrifice for the sins of His people. Because He is the covenant head of His people, He acted for all His elect, and they acted in Him. When He obeyed, they obeyed; when He died, they died; when He rose from the dead, they arose. Thus, the guilt of their sin was imputed to Him as He hung on the cross, satisfying the wrath of God; therefore, their sins are forgiven (Rom. 3:24–26). Furthermore, because Christ obeyed the Law perfectly, His perfect obedience is imputed to them, and God declares them to be righteous (Rom. 6:7; 2 Cor. 5:21). This pardon and imputation of righteousness is the believer’s justification.
Second, the believer is in union with Christ by conversion. What Christ did for us legally, while on earth, becomes ours personally when we are born again and repent and believe in Him (conversion). When we are converted we are engrafted into Christ personally as His Holy Spirit indwells us. This personal union with Christ is the basis of sanctification.
With respect to sanctification, two things occur at our conversion. First, because of our union with Christ, when we are born again, the old man dies (Rom. 6:6). In conversion, Christ’s death is applied to us so that our sinful nature is put to death; therefore, we are dead to sin. Although God in His providence has left a remnant of sin within us and we must labor to kill it (mortification), our union with Christ in His death guarantees the results of mortification.
Second, when we are born again, we are freed from the power of sin. Paul says the power that raised Christ from the dead is the power that regenerates us and is at work in us (Rom. 6:8, 9; Eph. 1:18–20). Therefore, we live by the power of the resurrection (Gal. 2:20), and thus, because of our union with Christ, the work of mortification will not fail.
How, then, do we apply our union with the death and resurrection of Christ to our fight against sin? First, Paul calls us to practice the duty of spiritual, positive thinking (Rom. 6:11). The power of positive thinking is an erroneous doctrine, but there is power in spiritual thinking. Paul exhorts us to think spiritually about our union with Christ and reckon ourselves dead to sin.
When you are faced with temptation, when lusts rise up within to attack you, consider yourself dead to sin. When you grieve over your lack of love for God and growth in grace, remind yourself, I am alive in Christ; I can grow in holiness. Practice the power of spiritual thinking.
Second, practice the duty of spiritual enlistment. Paul uses a military concept in verses 12–13. Since sin is no longer our master, we must not let it reign in our bodies to obey its lusts. He uses the term body, since the perversions of sin in the soul often manifests themselves in the bodily appetites and the body becomes an instrument of sin — our eyes, our speech, our hands, and our feet.
Paul says, quit enlisting the members of your bodies in service to sin, but rather present yourselves to God as those alive from the dead and belonging to God. Mortification results from our consecrating ourselves to God.
Third, make use of your baptism. Because of union with Christ, baptism is a God-appointed tool to help us mortify sin. Paul uses baptism in verses 3–4 to prove that we are not to continue in sin.
The Westminster Larger Catechism answers the question (#167), “How is our baptism to be improved by us?” with the following:
“The needful but much neglected duty of improving our baptism, is to be performed by us all our life long, especially in the time of temptation, and when we are present at the administration of it to others; by serious and thankful consideration of the nature of it, and of the ends for which Christ instituted it, the privileges and benefits conferred and sealed thereby, and our solemn vow made therein; by being humbled for our sinful defilement, our falling short of, and walking contrary to, the grace of baptism, and our engagements; by growing up to assurance of pardon of sin, and of all other blessings sealed to us in that sacrament; by drawing strength from the death and resurrection of Christ, into whom we are baptized, for the mortifying of sin, and quickening of grace; and by endeavouring to live by faith, to have our conversation in holiness and righteousness, as those that have therein given up their names to Christ; and to walk in brotherly love, as being baptized by the same Spirit into one body.”
“Improve” means to appropriate baptism in our lives. Note particularly we appropriate the benefits of baptism “by drawing strength from the death and resurrection of Christ, into whom we are baptized, for the mortifying of sin, and quickening of grace.” Our baptism reminds us that we are in union with Christ and have died to sin and its power. As we reflect on our baptism and its significance, we draw strength from the death and resurrection of Christ. Further, our baptism reminds us of our obligation to repent, mortify our sin, and pursue holiness. Baptism, therefore, is a useful bridge linking what we are in Christ to the fight against temptation and sin.
Our union with Christ guarantees our mortification. Let us remind ourselves of the power that is ours in Christ, enlist our bodies in the service of righteousness, and use our baptism as a means to these ends.