This pericope springs from the Apostle Paul’s great baptismal exposition in 6:1-11. Here, in 6:12-23, Paul conveys the consequences of being united to Christ’s death and resurrection. In fact, for the next nineteen consecutive weeks after Trinity Sunday, the pericopes from Romans and Philippians have this as their focus: The real-world implications of Christ’s death and resurrection upon those baptized “in Christ.” The preacher, then, has ample time to preach the Gospel from Romans along with the kingdom ethic which follows for those justified by God’s grace through faith because of Jesus Christ our Lord.
The preacher will want to sustain the connection with the preceding section, especially launching from 6:10: Christ, “died to sin once for all.” So, the Apostle’s thinking goes, when “we were baptized into Jesus Christ” (6:3), “we died to sin” (6:2). The verses following articulate how the baptized, therefore, are to “count” or “reckon” themselves also dead to sin through baptism.
Ok, now what? The struggle, which comes in the form of a life-long skirmish to believe it is true and live a life of faith in the Spirit.
Michael P. Middendorf aptly sums up Paul’s intent:
“The imperative of 6:12 is an ongoing warning: ‘Therefore, continually resist the reign of sin in your mortal body which results in being responsive to its desires.’ Paul exhorts baptized believers to engage in an ongoing refusal to allow sin to regain its dominance.”
Sin gains dominance within one’s “mortal body.” The referent “body” means the entire person in a physical body, but this body is subject to the consequence of sin, which is death. Thus, Paul describes the physical body within this fallen world, with the upshot being that the struggle with sin pertains to embodied life in this world.
Paul’s teaching could not be more direct: When the baptized neglect obedience to God, then the moral body (the entire embodied person) succumbs to sin’s dominance. The “struggle” may be expressed through auditory terms. You can hear the Word of God or harken to the “desires” of the mortal body, also known as the infamous “desires of the flesh.”
Paul’s teaching could not be more direct: When the baptized neglect obedience to God, then the moral body (the entire embodied person) succumbs to sin’s dominance.
Douglas Moo comments on “desire” here and in Romans 1:24, saying:
It “refers to desires that are in conflict with the will of God… These ‘passions’ would include not only the physical lusts and appetites but also those desires that reside in the mind and will: The desire to have our own way, the desire to possess what other people have (refer to 7:7-8), the desire to have dominance over others.”
Thus, a view which sees only the physical body as problematic misses the teaching of Scripture that places the impetus for sin in human nature itself, otherwise dubbed the “flesh” or, synonymously, the “mortal body.”
The Christian rejoices to have been justified freely by God’s grace because of Christ Jesus, as well as to have received the Holy Spirit. Justification and regeneration are the gifts of God through the Gospel Word preached and applied in baptism, but the Christian still retains the mortal body, which is ever endeavoring to get the upper hand. Neither the world nor the Devil will aid in the struggle against sin. Instead, they will bombard the baptized with every ungodly enticement to which they, by natural inclination, are so easily entangled.
Therefore, Paul preaches, “Do not continue to present your bodily members to sin as instruments of unrighteousness” (6:13). Verses 12-13 insist the baptized face an on-going alternative, obedience or bondage. The Apostle urges them to actively and continually oppose a return to being enslaved to sin. The differences between the two arrange contrasts at all levels: Truth verses falsehood, freedom verses slavery, holiness verses sin, light verses darkness, and life verses death.
Considering biblical anthropology, recapitulated by Paul in Romans 3, the startling things is that an alternative exists for the baptized! They have been justified. They have been regenerated. They have the Spirit. They belong to Christ and abide in His Kingdom. Therefore, Paul urges here and straight through chapter twelve that all the baptized, “Present your bodies as a living sacrifice, holy and acceptable to God... [and] be transformed by the renewing of your minds” (12:1, 2).
The trajectory of the remaining verses continues this theme with the analogy and reality of slavery (everybody serves somebody or something! 6:15-16), freedom from slavery by God (6:17-18), how the baptized are freed for slavery to God (6:19), and, lastly, the before and after fruits of these opposing bondages (6:20-22).
Nevertheless, while these verses presuppose the Gospel as their antecedent, Paul emphases the expectation and provision by God (through the Spirit and the power of the Gospel and Sacraments) to live within the ethic of Christ’s Kingdom. In short, these verses tend toward the imperative. Notwithstanding, the pericope does not end there. Verse 6:23 sounds the sweet notes of the Gospel regarding God’s gracious gift: “For the payment of sin is death, but the gracious gift of God is eternal life in Christ Jesus our Lord.” Jesus Christ has deposed the lordship of sin and its reign. Nothing can stand to oppose those who are in Him. They have been freed from slavery to sin and are now enslaved to a new Master and Lord.
Therefore, a truly evangelical reading of Romans 6 rightly articulates the doctrines of justification, regeneration, and sanctification. Be careful to not conflate or confusticate them and slide the expectant ethic of the post-baptismal Kingdom into that which justifies the sinner.
Concordia Theology-Various helps from Concordia Seminary in St. Louis, MO to assist you preaching Romans 6:12-23.
Text Week-A treasury of resources from various traditions to help you preach Romans 6:12-23.
 Middendorf, Romans 1-8. Concordia Commentary Series (St. Louis: Concordia Publishing House, 2013), 493.
 Moo, The Epistle to the Romans. New International Commentary on the New Testament (Grand Rapids: Eerdmans, 1996), 383.