“Justification is monergistic. Sanctification is synergistic.” Perhaps you’ve heard that explanation of the relationship between justification and sanctification. What do you think of it? At first and for a long time, I found it helpful. I first heard it from RC Sproul (full disclosure: I love RC Sproul. I’m Reformed today – and a pastor in the PCA – because of his ability to communicate the riches of Reformational theology in a clear, accessible way. I’m sure countless others could attest to that as well. I continue to benefit from his work, and use Ligonier resources in my congregation. Bottom line: RC is way smarter than me, and better looking, too). However, with all due respect to RC, I don’t think that’s the best way to put it. For a time, I heard that second statement, “sanctification is synergistic,” and translated it in my mind this way: “God does His part, I do mine.” Philippians 2:12-13, of course, is the proof of that proposition – or so I thought. (Check out Calvin’s commentary on this passage. He addresses verse 13 first, since the “good inclination [to work out our salvation with fear and trembling] is wholly the work of God.”)
The past year or so, the Reformed blog-o-sphere has been lit up over this issue of “effort in sanctification.” It’s been a good and helpful debate between brothers – although perhaps at times a bit reactionary. One thing that seems to be missing, though, is an engagement with Reformed Confessional standards. As I read Westminster, for example, I find such expressions as “sanctification is synergistic” or “effort in sanctification” woefully inadequate.
Consider Westminster Shorter Catechism (WSC) 35: “Sanctification is the work of God’s free grace, whereby we are renewed in the whole man after the image of God, and are enabled more and more to die unto sin, and live unto righteousness.” That first phrase alone makes emphatically clear that our sanctification is the work of God’s free grace – that is, the sovereign, undeserved favor of God. It is a WORK of God’s free grace – on-going – as opposed to a one-time (but ever-relevant!) ACT of God’s free grace – as we enjoy in our justification and adoption (WSC 33 & 34).
Notice also the passive language. By this work of God’s free grace, we “are renewed… after the image of God” and “are enabled more and more,” etc. God does the renewing. God does the enabling. Yes, having been enabled, we are implicitly involved in our sanctification. But this is no 50-50 proposition. We don’t share credit with God. Since it is “of God’s free grace,” He gets all the glory for any degree of sanctification in our lives.
Westminster Larger Catechism (WLC) 75 expands on what exactly this work of God’s grace encompasses: it is “through the powerful operation of His Spirit applying the death and resurrection of Christ unto [us],” etc. Sanctification is God’s gracious work, by His Spirit – and it is the application of Christ’s work FOR us TO us, specifically, His death and resurrection. The Westminster Divines would have in view Romans 6:4-6, etc. This is such an important point. Our sanctification is not only of God’s grace, it is Christ-centered. Christ is our righteousness and our sanctification. And so we see that sanctification is the work of the Triune God of grace.
Westminster Confession of Faith (WCF) 13, “Of Sanctification,” also emphasizes that sanctification is God’s work, first and foremost. Notice again the use of passive language when referring to the Christian. For example, WCF 13.1: “They… are further sanctified… and they more and more quickened and strengthened in all saving graces, to the practice of true holiness…” etc. God effectually calls us, regenerates us, and further sanctifies us “through virtue of Christ’s death and resurrection, by His Word and Spirit dwelling in [us],” etc. All of this results in the Christian practicing “true holiness.” But again, our sanctification is entirely the result of God’s initiative and grace to us in Christ.
WCF 13.2 affirms that sanctification is throughout the “whole man,” yet imperfect in this life. In fact, every part of the regenerate person has the remnants of corruption. This, by the way, is applicable to recent debates on whether a Christian is “totally depraved.” To be sure, according to Westminster (which is simply confessing Scripture’s teaching – see Romans 7:13-25 and Galatians 5:16-18), we do indeed have remaining corruption in every part of our humanity. We are not totally depraved in the sense of being unregenerate / spiritually dead. But we are still “corrupt in every part” of our humanity. And so sanctification is an on-going war between our flesh, and the God-given Spirit. Here again, sanctification is more something that is happening to us and within us – rather than something we are doing as “equal partners” with God’s Spirit.
Finally, WCF 13.3 continues the warfare theme of the prior section, even acknowledging that “the remaining corruption, for a time, may much prevail.” Yet we do not despair in this warfare. Because God in His grace provides a “continual supply of strength from the sanctifying Spirit of Christ” which assures us “the regenerate part doth overcome.” It concludes, “…and so [that is, in this way], the saints grow in grace, perfecting holiness in the fear of God.” Again, the emphasis is on God’s work, God’s grace, God’s Son, and God’s Spirit in our sanctification.
So, does that mean we “let go and let God”? Does that mean there is no place for effort in the Christian life? By no means!
Westminster makes clear the Christian life is one of effort. NOT in sanctification per se – which is the work of God’s free grace in us – but in GOOD WORKS. This is where Westminster places the emphasis on our diligent effort in the Christian life.
First, a quick survey of this excellent chapter. In WCF 16, Westminster first reminds us from Scripture that “good works” are only those which God commands in His holy Word, i.e., HIS Law, HIS commandments, HIS imperatives – not our “blind zeal” or “pretense of good intention” (WCF 16.1). Here, “good works” especially refer to our duties in the Christian life. Westminster is rejecting the “commandments of men,” the conscience-binding duties imposed by an overreaching church apart from the Word (whether Rome or Canterbury – think penance and prayer books). I want to emphasize this. Good works are outward and observable. They are indeed the fruit of a “true and lively faith,” (16.2) and thus the outward expression of our sanctification. We can’t “see” the degree of one’s sanctification inwardly. We can only see the evidence of that sanctification OUTWARDLY, as expressed in good works.
WCF 16.2 affirms the excellence and usefulness of good works. 16.3 affirms that the Holy Spirit is the one who enables us to do good works. 16.4 reminds us that there are no “super-saints” who do more than God requires – but rather that we all fall short in much of our duties. 16.5 teaches that good works are not meritorious. The Holy Spirit alone gets credit for any “good” in our good works. For our part, the dirty fingerprints of our flesh defile our works – and would render them rejected if not for Christ, in whom we and our works are graciously accepted by God (16.6). 16.7 teaches that unregenerate men can do things which are useful to themselves and others. But they cannot do truly “good works” – because they are without Christ, the Spirit, the Word, and the right end: the glory of God.
So where do we find Westminster’s emphasis on effort in the Christian life, namely, in good works? Back to WCF 16.3: After we are reminded that the Holy Spirit alone enables us to do good works – and that His influence is essential to any truly good work – yet we are not “hereupon to grow negligent, as if [we] were not bound to perform any duty unless upon a special motion of the Spirit; but [we] ought to be diligent in stirring up the grace of God that is in [us].” No “letting go and letting God” in the Christian life! We have Christian DUTIES – outward and observable things we are to diligently DO – in the Christian life.
In fact, one of our duties is to stir up the grace of God that is in us. Yet if this is truly a good work, it too is the result of God’s sanctifying work within us. Nonetheless, WE are to do it! And as we do, by the grace of God, we will grow in the grace and knowledge of the Lord. This is where we can see an essential connection between our duty in good works and our sanctification.
Consider what we call “the means of grace” and our duties in light of them. The first table of the Ten Commandments conveys our duty to worship God. And so we apply ourselves to the public ministry of the Word, the Sacraments, and prayer. We are not to “forsake the assembling of ourselves together” (Heb 10:25). And as we apply ourselves to these means of grace, God sanctifies us. We hear the Gospel preached, we see it and taste it in the sacraments, and we give thanks to God for it. By these Gospel means, God strengthens our faith, which bears fruit in love – and we walk in good works. Because it is “God who works in us, to will and to do according to His good pleasure,” therefore we “work out our salvation with fear and trembling.”
“Sanctification is synergistic”? Maybe not the best way to put it. “Effort in sanctification”? Not very helpful, either. “Effort in GOOD WORKS,” i.e., the outward duties of the Christian life carried out in gratitude for God’s grace to us in Christ – most DEFINITELY!
Perhaps Martin Luther’s words about faith and good works are fitting here in conclusion: “O it is a living, busy, active, mighty thing, this faith. It is impossible for it not to be doing good works incessantly. It does not ask whether good works are to be done, but before the question is asked, it has already done them, and is constantly doing them. Whoever does not do such works, however, is an unbeliever. He gropes and looks around for faith and good works, but knows neither what faith is nor what good works are. Yet he talks and talks, with many words, about faith and good works.” 
 Luther, M. (1999). Vol. 35: Luther’s works, vol. 35 : Word and Sacrament I (J. J. Pelikan, H. C. Oswald & H. T. Lehmann, Ed.). Luther’s Works (370). Philadelphia: Fortress Press.