Here and now, slaves to God and righteousness struggle to resist sin and temptations to sin. Dedicated sanctified living remains a struggle (cf. Rom 6:11-19). Middendorf observes, “In 6:11-19, Paul uses five imperatives to exhort the Baptized to resist sin, and instead, to offer themselves in willing service to God.”[1] To resist sin and offer oneself willingly exemplifies the responsiveness of a slave to God and to righteousness. The struggle persists in this present age (cf. Rom 7:7-25). Paul urges, “Therefore continually resist the reign of sin in your mortal body which results in being responsive to its desires” (Rom 6:12). Responding to the desires of the sinful flesh is not resisting sin. The implication that sin is a struggle gives the reason for this imperative to resist sin’s attempts to regain its reign in the mortal flesh.
Additionally, Paul addresses resisting sin already at the beginning of Romans 6: “What then will we say? Let us persist in sin so that grace might multiply? May it never come to be! We who died to sin, how will we still live in it?” (6:1-2). Paul’s rhetoric implies an existing struggle against sin in the mortal body (cf. Rom 6:12), and to offer oneself willingly to serve God in righteousness for the sake of Christ. The slave of Christ should not persist in sin to multiply sin, but persist in righteousness that multiplies on account of Christ’s grace.
The imperatives to resist sin and the desires of the flesh are vital to counterattacking the stench of sin. Sin is an offensive failure that falls short of God’s glory. The term “sin” is derives from “ἁμαρτία-hamartia, a sin, failure.”[2] Yet grace covers the sinners' offenses on account of Christ. By grace the Christian is also freed from sin’s bondage, and then exhorted to sanctified living which involves resisting sin.
In the now/not yet, sin remains a struggle in mortal human hearts. The renewed slave to God battles with the human nature and desire to sin. The imperatives of Paul are only applicable to those in Christ who remain simul iustus et peccator. Middendorf warns against misunderstandings of the simul:[3]
Paul’s exhortations make no sense to an unbeliever; they make no sense to those who are still slaves to sin, even if that slavery is cleverly masquerading itself as slavery to some supposedly autonomous self. The ongoing struggle expressed in 6:12–23 also betrays the notion that holiness of living is somehow temporally attainable, rather than a continual battle this side of eternity. Yet they also do not make sense if our struggle against sin and our efforts to live for God are a matter of complete futility and, therefore, not to be energetically pursued. Such resignation to sin is an improper appropriation of Luther’s “sin boldly” and a simplistic misapplication of simul justus et peccator. Both Paul’s indicatives and his imperatives are also not properly comprehended if one adopts a “God-does-it-all-so-I-can-be-lazy” attitude toward sanctified living. Yes, God does it all in our justification (e.g., 3:21–26, 28). We do well to reject all moralism and legalism. At the same time, we ought to confess that an indolent apathy is not what Paul teaches about sanctification.[4]
Imperative statements to the unbeliever are incomprehensible and hidden to those who struggle against sin apathetically are under moralistic legalism. Slaves to Christ are justified from sin and sanctified, set apart as holy to God on account of Christ. That is why they struggle with the sinful nature.
Peter similarly speaks of the freedom from sin, exhorting sanctified Christians to live in Christ in responsiveness to righteousness and not for responsiveness to evil and sin. He writes, “Live as free people, but do not use your freedom as a cover-up for evil; live as God's slaves” (1 Pet 2:16). Luther also observed the Christian struggle with sin:
The Christian life is, namely, a trial, warfare, and struggle. It is clear how those who are being tried by various shocks are to be trained, so that they do not despair if they have not yet felt that they are free from the evil prompting of any sin whatever. Thus in Rom. 13:14 Paul says: “And make no provision for the flesh, to gratify its desires.” And in Rom. 6:12 he says: “Let not sin reign in your mortal bodies, to make you obey its passions.” No one can avoid desire, but it is possible for us to keep from obeying the desires.[5]
In short, the Christian demonstrates these truths of sanctified living under grace as an instrument of righteousness fighting to resist the reign of sin and evil in the body.
Instruments of Righteousness
On the positive side, the Christian is to be an instrument [ὅπλα][6] of righteousness under grace. After being freed and declared righteous from sin, Paul exhorts Christians to live in sanctification, presenting themselves as instruments of righteousness. Paul writes: “And do not continue to present your bodily members to sin [as] instruments of unrighteousness; instead, present yourselves to God as living from [the] dead and your bodily members to God [as] instruments of righteousness” [7] (Rom 6:13; cf. 2 Cor 6:7). Paul’s second imperative here is to offer one's body as an instrument of God living from the dead in Christ. This recalls the previous exhortation to resist the reign of sin in the body (cf. Rom 6:12). An instrument of righteousness lives to righteousness as a slave to God. One could say that a Christian is a tool and weapon of God for righteous living.
[1] Middendorf, Romans 9-16, 1196.
[2] “ἁμαρτία, ίας, ἡ . . . ① a departure fr. either human or divine standards of uprightness ⓐ sin . . . ③ a destructive evil power, sin . . . Sin under Law: NTS 14, ’67/68, 424–39), reigns there vs. 21; 6:14; everything was subject to it Gal 3:22; people serve it Ro 6:6; are its slaves vss. 17, 20; are sold into its service 7:14 or set free from it 6:22; it has its law 7:23; 8:2; it revives (ἀνέζησεν) Ro 7:9 or is dead vs. 8; it pays its wages, viz., death 6:23, cp. 5:12 (see lit. s.v. ἐπί 6c). As a pers. principle it dwells in humans Ro 7:17, 20, viz., in the flesh (s. σάρξ 2cα) 8:3; cp. vs. 2; 7:25. The earthly body is hence a σῶμα τῆς ἁ. 6:6 (Col 2:11 v.l.).—As abstr. for concr. τὸν μὴ γνόντα ἁ. ὑπέρ ἡμῶν ἁμαρτίαν ἐποίησεν (God) made him, who never sinned, to be sin (i.e. the guilty one) for our sakes 2 Cor 5:21.” BDAG, 50-51; “ἁμαρτία hamartia; from G264; a sin, failure: — sin.” NASEC, G266.
[3] Compare simul with pecca fortiter–“sin boldly”; e.g., Luther said: “Be a sinner and sin boldly, but believe and rejoice in Christ even more boldly, for he is victorious over sin, death, and the world.” AE 48:282; Cf. Bonhoeffer, The Cost of Discipleship, 52-53.
[4] Middendorf, Romans 1–8, 510; “As the Formula of Concord states: ‘From this it follows that as soon as the Holy Spirit has initiated his work of regeneration and renewal in us through the Word and the holy sacraments, it is certain that we can and must cooperate by the power of the Holy Spirit, even though we still do so in great weakness.’ (FC SD II 65).” Ibid., 511.
[5] Luther, “Lectures on Galatians Chapters 1-6” (1519), AE 27:361.
[6] “ὅπλα ἀδικίας—The neuter noun ὅπλον denotes an ‘instrument’ or ‘tool’ (BDAG, 1). It can have the military connotation of a ‘weapon’ (BDAG, 2, citing 2 Cor 6:7; 10:4), but the more general sense applies here. The plural form ὅπλα here, along with μέλη, forms a double accusative construction, necessitating the insertion of ‘as’ in translation. ὅπλα is then modified by the genitive of ἀδικία, ‘unrighteousness’ (see … [Rom] 1:18; also 1:29; 2:8; 3:5; 9:14), but later in the verse it is used with the dative of δικαιοσύνη, ‘righteousness.’” Middendorf, Romans 1–8, 488.
[7] Notably, the words of Paul are echoed in The Letter of Polycarp to the Philippians as an imperative for the church to be armed with weapons of righteousness and follow the commandment to love God and love neighbor and not the world and money. Polycarp wrote, “But the love of money is the beginning of all troubles. Knowing, therefore, that we brought nothing into the world and cannot take anything out, let us arm ourselves with the weapons of righteousness, and let us first teach ourselves to follow the commandment of the Lord” (4:1). Michael W. Holmes, The Apostolic Fathers: Greek Texts and English Translations, 3rd ed. (Grand Rapids, MI: Baker Academic, 2007), 285.