No Lutheran who confesses that the Book of Concord is a correct exposition of Holy Scripture can deny that the regenerate man cooperates with the Holy Spirit in new obedience. It is impossible to deny this because the Formula of Concord explicitly states this teaching:
On the one hand, it is correct to say that in conversion God changes recalcitrant, unwilling people into willing people through the drawing power of the Holy Spirit, and that after this conversion the reborn human will is not idle (wiedergeborner Wille nicht müßig gehe) in the daily exercise of repentance but cooperates (auch mitwirke) in all the works of the Holy Spirit which he performs through us” (FC Ep II.17).
For when the Holy Spirit has effected and accomplished new birth and conversion and has altered and renewed (aeändert und erneuert) the human will solely through his divine power and activity, then the new human will is an instrument and tool of God the Holy Spirit, in that the will not only accepts grace but also cooperates (mitwirket) with the Holy Spirit in the works that proceed from it” (FC Ep II.18).
It follows from this, as has been said, that as soon as the Holy Spirit has begun his work of rebirth and renewal in us through the Word and the holy sacraments, it is certain that on the basis of the his power we can and should be cooperating with him (mitwirken können und sollen), though still in great weakness. This occurs not on the basis of our fleshly, natural powers but on the basis of the new powers and gifts which the Holy Spirit initiated in us in conversion, as St. Paul specifically and earnestly admonished, that “as we work together with” the Holy Spirit “we urge you not to accept the grace of God in vain” [2 Cor. 6:1] (FC SD II.65-66).
It has been sufficiently explained above how God makes willing people (Willige) out of rebellious and unwilling people through the drawing power of the Holy Spirit, and how after this conversion of the human being the reborn will is not idle (nicht müßig gehe) in daily practice of repentance but cooperates (mitwerke) in all the works of Holy Spirit that he accomplishes through us” (FC SD II.88).
The Scriptures teach that the individual Christian is both new man and old man at the same time (Rom 7:13-23; Gal 5:16-17; Col 3:5-15). In Christ through the work of the Spirit the new man knows God’s will and lives according to it. Because they are individuals in whom the old man still exists, this new life does not occur perfectly and instead occurs in the midst of struggle and weakness. Naturally, the Lutheran Confessions also present this view of Christians as old man and new man at the same time (for example FC SD II.84-85; VI.6-8).
While it is true that we must always add all of the caveats about how the presence of the old man impacts the individual Christian, this does not change the fact that in regeneration the Spirit has actually done something to the individual and brought about a change. Scripture teaches that through the work of the Spirit in Holy Baptism the Christian has been born again and received regeneration (John 3:3, 5; Tit 3:3-5), and that through the work of the Spirit he is a “new creation”: “Therefore, if anyone is in Christ, he is a new creation. The old has passed away; behold, the new has come” (καινὴ κτίσις· τὰ ἀρχαῖα παρῆλθεν, ἰδοὺ γέγονεν καινά) (2 Corinthians 5:17 ESV) (see also Gal 6:15).
Paul writes in Rom 7:22-23, “For I delight in the law of God, according to my inner man (κατὰ τὸν ἔσω ἄνθρωπον), but I see in my members another law waging war against the law of my mind (τῷ νόμῳ τοῦ νοός μου) and making me captive to the law of sin that dwells in my members.” Paul goes on to say in Rom 8:5-6, “For those who are according to the flesh think the things of the flesh (τὰ τῆς σαρκὸς φρονοῦσιν), but those who are according to the Spirit think the things of the Spirit (τὰ τοῦ πνεύματος). For the mind of the flesh (τὸ γὰρ φρόνημα τῆς σαρκὸς) is death, but the mind of the Spirit (τὸ δὲ φρόνημα τοῦ πνεύματος) is life and peace” (Romans 8:5-6). The subject doing the thinking does not cease to be the individual. Paul says that “they think” (the φρονοῦσιν of 8:5a must be supplied in 8:5b). Regenerated by the Spirit the new man now is able to think in the ways of the Spirit, namely, the things that reflect God’s will. True, it is only through the continuing work of the Spirit that this is possible, because otherwise the old man, the mind of the flesh will gain complete control as he does in the non-Christian. Nevertheless, the existence of the individual as new man is not lost. Regenerated, sustained and led by the Spirit, the new man is able to begin to cooperate in the new obedience that faith produces.
This is the position of the Lutheran Confessions. A real change is brought about. In fact, if it were not for the continuing presence of the old man, the Christian would be completely obedient due to the regenerated will. The Formula of Concord states: “Indeed, if the faithful and elect children of God were perfectly renewed through the indwelling Spirit in this life, so that in their nature and all their powers they were completely free from sin, they would need no law and therefore no prodding. Instead, they would do in and of themselves, completely voluntarily, without any teaching, admonition, exhortation, or prodding of the law, what they are obligated to do according to God’s will, just as in and of themselves the sun, the moon and all the stars follow unimpeded the regular course God gave them once and for all, apart from any admonition, exhortation, impulse, coercion, or compulsion. The holy angels perform their obedience completely and of their own free will” (FC SD VI.6).
For this reason, when it comes to new obedience the Lutheran Confessions say that the new man in the individual cooperates with the Spirit in new obedience. Justification is a result of divine monergism. Sanctification (understood in the narrow sense) is a result of divine monergism. But new obedience takes place through synergism of the new man working with the Spirit.
Now there is no doubt that the new man is able to do this only because of the Spirit’s regeneration and because of the continuing work of the Spirit in the individual. It is also clear in the Confessions that it is the Spirit who leads the new man in doing these things. The Formula clarifies the language of “cooperation” by saying, “This should be understood in no other way than that the converted do good to the extent that God rules, leads, and guides them with his Holy Spirit. If God would withdraw his gracious hand from such people, they could not for one moment remain obedient to God. If this passage were understood as if the converted person cooperates alongside the Holy Spirit, the way two horses draw a wagon together, this interpretation could not be tolerated without damaging the divine truth” (FC SD II.66). Nonetheless, because of the change that Spirit has worked and sustains in the new man the Confessions in unambiguous language say that the new man cooperates with the Spirit.
These basic facts are not in dispute among confessional Lutherans. However, in recent years an interpretation of the term “cooperation” has appeared that seeks to affirm the word, but redefine it in a way that denies what the Scriptures and Confessions teach. It carries divine monergism into the new obedience of the life a Christian now lives. This view takes up the correct emphasis on the priority of the Spirit in the life of the regenerate, but because it fears the potential for abuse in any teaching about synergism, it then emphasizes the Spirit to the point that the individual will of the Christian ceases to exist in any meaningful way. The individual Christian as an individual is completely lost and is swallowed up by the work of the Spirit.
Crucial for this view is the language in FC Ep II.18: “For when the Holy Spirit has effected and accomplished new birth and conversion and has altered and renewed the human will solely through his divine power and activity, then the new human will is an instrument and tool (Instrument und Werkzeug) of God the Holy Spirit, in that the will not only accepts grace but also cooperates with the Holy Spirit in the works that proceed from it” (FC Ep II.18).
Based on this language, it is argued that "cooperates" means nothing other than being an instrument or tool of the Spirit. That is to say the regenerate will is simply the means through which Spirit operates. On this view, the Christian is like a saw used by the carpenter. It is God who through regeneration has made the Christian usable in this way. But just as the saw does not in any real way cooperate (it has no volition or intent), so the Christian is simply the tool used by the Spirit to produce new obedience.
In a similar manner, language that emphasizes the priority of the Spirit such as FC SD II.65-66 is seen as proof that “cooperation” is being used in a unique way that does no conform to our normal expectations:
It follows from this, as has been said, that as soon as the Holy Spirit has begun his work of rebirth and renewal in us through the Word and the holy sacraments, it is certain that on the basis of the his power we can and should be cooperating with him, though still in great weakness. This occurs not on the basis of our fleshly, natural powers but on the basis of the new powers and gifts which the Holy Spirit initiated in us in conversion, as St. Paul specifically and earnestly admonished, that “as we work together with” the Holy Spirit “we urge you not to accept the grace of God in vain” [2 Cor. 6:1]. This should be understood in no other way than that the converted do good to the extent that God rules, leads, and guides them with his Holy Spirit. If God would withdraw his gracious hand from such people, they could not for one moment remain obedient to God. If this passage were understood as if the converted person cooperates alongside the Holy Spirit, the way two horses draw a wagon together, this interpretation could not be tolerated without damaging the divine truth.
However, this view is wrong for four reasons. The first thing to note is that it makes the word “cooperation” meaningless. Cooperation in both its Latin and Greek (synergism) forms emphasizes a working together. The word assumes that some effort or action is being contributed by at least two parties. This action need not be equal. When my eight year old son helps me in a house project, he is certainly not an equally contributing partner. He is, however, taking part and doing those things that he is able to do as he follows my lead. However, to attempt to redefine cooperation so that one party does nothing except to be used by the other renders the word pointless.
Second, this view is unable to handle the language of Scripture. Verse after verse describes the Christian as living and acting as a result of Christ’s saving death and resurrection. Paul says in Rom 6:4, “We were buried therefore with him by baptism into death, in order that, just as Christ was raised from the dead by the glory of the Father, we too might walk in newness of life” (ESV). Here it is the Spirit who provides the link between Jesus’ resurrection and the ability to walk in newness of life, because the Spirit who raised Jesus from the dead is in the believer (Rom 8:11). The Spirit alone is the One who makes it possible, but it is the Christian who actually seeks to engage in new obedience. Regeneration does not change this fact. Instead, it makes it possible for the Christian to pursue this course of action as he cooperates with the Spirit.
Third, the key text about the regenerate will as an instrument and tool (Instrument und Werkzeug) of the Spirit is actually set in contrast to the human will being purely passive. Thus the preceding statement of FC EP II.18 is: “Likewise, when Dr. Luther wrote that the human will conducts itself pure passive (that is, that it does absolutely nothing at all), that must be understood respectu divinae gratiae in accendendis novis motibus [in respect to divine grace in the creation of new movements], that is, insofar as the God’s Spirit takes hold of the human will through the Word that is heard or through the use of the holy sacrament and effects new birth and conversion.” In other words, when the regenerate will is described as cooperating with the Holy Spirit, the Confessions are setting this in opposition to the purely passive state of the unregenerate will in the process of conversion. Therefore the second half of FC EP II.18 cannot mean that the regenerate will is merely the passive tool used by the Spirit as this position asserts.
Finally, the Confessions do not make such an error. Instead, while emphasizing the priority of the Spirit, they never lose sight of the fact that in regeneration the Spirit actually does something to the will of the individual. Through the sustaining and leading work of the Spirit, the regenerate will is able to cooperate – it takes part and shares in the doing. The Formula of Concord is filled with language that is not patient of the view described above. It has abundant language about the attitude and activity of the regenerate will:
The Christian acts from a willing heart: This is true also because they act in a God-pleasing way – not because of the coercion of the law but because of the renewal of the Holy Spirit – without coercion, from a willing heart insofar as they are reborn in their inner person. At the same time they continually do battle against the old creature” (FC SD VI.23).
Christians have a willing spirit: “Believers, however, do without coercion, with a willing spirit, insofar as they are born anew, what no threat of the law could ever force them to do” (FC Ep VI.7)
Christians are willing people and the human will is not idle: “On the one hand, it is correct to say that in conversion God changes recalcitrant, unwilling people into willing people through the drawing power of the Holy Spirit, and that after this conversion the reborn human will is not idle (wiedergeborner Wille nicht müßig gehe) in the daily exercise of repentance but cooperates (auch mitwirke) in all the works of the Holy Spirit which he performs through us” (FC Ep II.17).
“It has been sufficiently explained above how God makes willing people out of rebellious and unwilling people through the drawing power of the Holy Spirit, and how after this conversion of the human being the reborn will is not idle in daily practice of repentance but cooperates in all the works of Holy Spirit that he accomplishes through us” (FC SD II.88).
Christians desire the good and delight in it: Although those born anew come even in this life to the point that they desire the good and delight in it and even do good deeds and grow in practicing them, this is not (as we mentioned above) a product of our own will or power; but the Holy Spirit, as Paul says himself, ‘is at work in us to will and work” (Phil. 2[:13]). He says the same thing in Ephesians 2[:10], when he ascribes these words to God alone: “We are what he has made us, created in Christ Jesus for good works, which God prepared beforehand to be our way of life” (FC SD II.39).
Christians desire to practice God’s law: For this reason the human being who is not reborn resists God completely and is totally the slave of sin. The reborn, however, desire to practice God’s law according to their inward self, but see at the same time in their members the law of sin, which resists the law of their mind. Therefore they serve God’s law with their mind but the law of sin with their flesh (Rom 7[:22, 23, 25) (FC SD II.85).
Christians do God’s will from a free and merry spirit: However, when people are born again through the Spirit of God and set free from the law (that is liberated from its driving powers and driven by the Spirit of Christ), they live according to the unchanging will of God, as comprehended in the law, and do everything, insofar as they are reborn, from a free and merry spirit (FC SD VI.17).
Christians have the new spiritual power and capability to do the good in their hearts: Therefore, on the basis of God’s Word we now want to give a further account of how the human being is converted to God: how and through which means (namely, through the oral Word and holy sacraments) the Holy Spirit desires to be active in us and to give and effect true repentance, faith, and the new spiritual power and the capability to do good works in our hearts; and how we should respond to such means and use them (FC SD II.48).
Christians have a free will and are able to accept God’s Word: Therefore there is a great difference between baptized and unbaptized people. For since (according to Paul’s teaching, Gal 3[:27]) “all those who have been baptized have put on Christ,” and there therefore truly reborn, they now have arbitrium liberatum [a free will or free choice], that is, as Christ says, “they have been made free again” [cf. John 8:36]. For this reason they not only hear the Word but are also able to assent to it and accept it – although in great weakness (FC SD II.67).
Christians have new impulses and movements in mind, will and heart: For, on the one hand, it is true that in a true conversion there must be a change – new impulses and movements in mind, will, and heart. As a result, the heart acknowledges sin, fears God’s wrath, turns away from sin, acknowledges and accepts the promise of grace, has good spiritual thoughts, Christian intention and diligence, battles against the flesh, etc. For where none of these things takes place or exists, there is no true conversion (FC SD II.70).
The massive presence of this kind of language leaves no doubt that the regenerate will of the Christian does cooperate with the Holy Spirit in new obedience. The Spirit uses the regenerate will as the instrument and tool to carry out new obedience and the regenerate will works with the Spirit in this new obedience.
Because of these statements in the Book of Concord it should not surprise us to learn that, the standard teaching throughout the Lutheran dogmatic tradition maintains that new obedience occurs as a result of cooperation by the new man with the work of the Spirit. It is synergistic. The following are a mere sample:
Chemnitz: "But how can good works be done by us, when the devil stalks us with his snares, the world is full of offenses, and sin itself dwells in our flesh? First of all it is necessary that the person be reconciled to God through faith for the sake of Christ. For thus the Holy Spirit is given in reconciliation itself (Gl 3:2, 14; Tts 3::5-6); He purifies and renews hearts (Acts 15:8-9; Ps 51:10; Eph 4:23; Eze 36:26); He will kindle new affections in [your] heart, that it submit itself to the Law and divine obedience (Ro 6:17; 7:22). For a tree must first be good, before goof fruits come forth from it (Mt 7:18; 12:33). But after the Holy Spirit has already begun in us that work of renewal, we also can and should add our effort, by following the leadership of the Holy Spirit and mortifying the works of the flesh through the Spirit (Rom 8:13; 12:2; 2 Ptr 1:5; 2 Ti 1:6). For through these exercises God wants to preserve and increase in us His gifts by the grace, power, and help of the Holy Spirit (1 Co 15:10; Mt 25:21, 29)."
Gerhard: “In this way the question pertains to the reborn who, we do not deny, are coworkers [συνέργους] with God in good works, because the will, now freed from the yoke of sin, cooperates by virtue of new powers granted by the Holy Spirit.”
Quenstedt: “The Holy Spirit produces in man, without human concurrence, the power to produce good works an the first act of sanctification; but man concurs in the second act of sanctification, or in the exercise and continuance of it, when once introduced by the Holy Spirit … The regenerate man co-operates with God in the work of sanctification, not by an equal action, but in subordination and dependence on the Holy Spirit, because he works, not with native but with granted powers.”
Hollaz: “Good works are not actions free from the necessity of obligation or duty, but are said to be actions from the necessity of constraint (because they are not extorted by the threats of punishment, or externally, and in appearance, performed contrary to will), and of immutability (since the will is no longer determined to the constant thought and preparation of evil, as before conversion; but can freely choose and do good works by supernatural strength, received from the Holy Spirit; can likewise choose evil works by the remains of the flesh, still adhering to it, since it is not determined to good as the angels are); and are performed by the regenerate, freed from the servitude of sin by the Holy Spirit (John 8:36; Rom. 6:18; 2 Cor. 3:17”).”
Schmid: “Finally, it is a work of God in man, yet of such a nature that there is a free co-operation on the part of man, who now in conversion has received new spiritual powers.”
Pieper: “Good works are God’s work. He is the causa efficiens of them. While the new man of the Christian co-operates in performing them, this co-operation is so completely subordinate to God’s operation that the Christian does the good only so far and long as God works in and through him.”
Laudably, those who wish to argue that cooperation is used in the Formula of Concord in a unique and unusual way fear that the old Adam will seize hold of this biblical synergism and use it in sinful ways. However, in order to avoid this they have imposed a false reading of the text that contradicts Scripture and the Lutheran Confessions. They propose an understanding that does not adequately account for God’s gracious and miraculous action in regeneration. For in regeneration the Spirit actually does something to the individual and this has tremendous implications for new obedience in the Christian life.
 The Latin translation has “renati voluntas non sit otiosa.”
 The Latin translation has “etiam cooperetur.”
 The Latin translation has “immutavit atque renovavit.”
 The Latin translation has “cooperetur.”
 The Latin translation has “cooperari possimus ac debeamus.”
 The Latin translation has “volentes.”
 The Latin translation has “non sit otiosa.”
 The Latin translation has “cooperetur.”
 In the Scriptures (1 Cor 6:11) and in the Confessions (such as the Small Catechism’s explanation to the Third Article of the Creed) the primary manner in which the word “sanctification” is used is to describe the way the Holy Spirit makes the believer holy in Christ by creating and sustaining faith. Justification has been provided on account of Christ. The Spirit applies this justification to the individual through the Means of Grace and through this work the believer stands forgiven and holy in Christ before God. Now it is true that Scripture does use the word “sanctification” to describe the holy life that results from regeneration and faith (1 Thess 4:3). It is also true that the Lutheran dogmatic tradition has used the term this way. However, because this is not the main way that Scripture and the Confessions use the term, and because this is the term used by other Christian traditions for an incorrect understanding, I believe it is best not to use the word to refer to Christian life that is produced by the Spirit in Christ. Instead, “new obedience” is the title given to this in Article VI of the Augsburg Confession and so it is a better choice.
 The Latin translation has “renati voluntas non sit otiosa.”
 Martin Chemnitz, Ministry, Word and Sacraments: An Enchiridion (tr. Luther Poellot; St. Louis: Concordia Publishing House, 1981), para. 199; pg. 101 (emphasis mine).
 Heinrich Schmid, The Doctrinal Theology of the Evangelical Lutheran Church (3d ed., rev.; trans. Charles A. Hay and Henry E. Jacobs; Minneapolis: Augsburg Publishing House, 1899), 491 (emphasis mine).
 Heinrich Schmid, The Doctrinal Theology of the Evangelical Lutheran Church, 498 (emphasis mine).
 Heinrich Schmid, The Doctrinal Theology of the Evangelical Lutheran Church, 487 (emphasis mine).
 Francis Pieper, Christian Dogmatics, vol. 3 (St. Louis: Concordia Publishing House, 1953), 60 (emphasis mine).