One of the chief benefits of the recent debates regarding sanctification is a renewed emphasis on the believer's union with Christ through faith. If we realize how often the apostle Paul situates our salvation "in Christ," we will also realize that Christ truly is the fountain of every spiritual blessing for the Christian. It is for this reason that the fourth affirmation of the Gospel Reformation Network on the gospel and sanctification highlights the centrality of union with Christ:

Many people today are confused by the language of union with Christ, but the meaning is simply that our every blessing in salvation flows from the person and work of Jesus Christ, to whom we are joined through faith. This was John Calvin's emphasis in the opening paragraph of Book Three of his Institutes, on "The Way in Which We Receive the Grace of Christ." Calvin wrote: "By faith... we come to enjoy Christ and all his benefits" (Institutes, III.1.1)." Calvin articulated his famous duplex gratia, the dual graces of justification and sanctification that mutually flow from union with Christ. This follows the two trajectories defined for the new covenant in Hebrews 8:10-12, one transformative and the other forensic: "I will put my laws into their minds and write them on their hearts... I will be merciful toward their iniquities, and I will remember their sins no more."  Calvin writes: "By partaking of him, we principally receive a double grace (duplex gratia), namely, that being reconciled to God through Christ's blamelessness, we may have in heaven instead of a Judge a gracious Father; and secondly, that sanctified by Christ's Spirit we may cultivate blamelessness and purity of life" (Institutes, III.11.1).

Understanding that both justification and sanctification flow from union with Christ, we must be careful to distinguish between them: "justification and sanctification are distinct... graces of union with Christ through faith." The danger of conflating justification and sanctification runs in both directions. On the one hand, we must never ground our justification in terms of our sanctification.  This is the crippling legalism which hinders so many Christians, who, on a day-to-day basis, ground their sense of acceptance with God on their spiritual performance. Justification is through faith, apart from works, because it relies solely on the finished work of Jesus Christ (Gal. 2:16) in both his active and passive obedience on our behalf (Rom. 5:12-19). At the same time, we must not conflate sanctification into justification, so that our growth in holiness is conceived merely as "resting upon our justification." The biblical commands to sanctification involve far more than resting, but call us to "strive" (1 Tim. 4:10), "work" (Phil. 2:12), "labor" (1 Thess. 1:3), and "put off"/ "put on" (Eph. 4:22-24).   

In addition to emphasizing the distinction between justification and sanctification, we must emphasize that they are, furthermore, "necessary, inseparable and simultaneous." Sanctification is not some add-on that may come after justification, but is integral to Christian salvation from the moment of our conversion and regeneration. Sanctification is as necessary to salvation as is justification, since both result from union with Christ (Eph. 2:10). To be sure, these two graces take different places in the believer's salvation, but it remains no more possible to be saved without sanctification than without justification. Moreover, since "faith without works is dead" (Ja. 2:17), we must emphasize that justification and sanctification are simultaneous in the believer's experience. The two are different, since we receive a whole and final justification when we believe, in contrast to a sanctification that requires nurture and growth. Yet it is of the nature of regeneration and saving faith that our new status in justification is always simultaneous with a new nature that is engaged in sanctification.

By emphasizing that justification and sanctification are necessary, inseparable, and simultaneous graces of union with Christ, we address a common misconception that has a significant effect on preaching and pastoral practice today. To this end, Article 4 includes this denial:

This denial addresses the question, "Does justification cause sanctification?" This question is important, since if the answer is "Yes," as many believe, then we gain sanctification merely by the preaching of justification. If sanctification is caused by preaching justification, then there is no value and perhaps much harm in teaching the Bible's commands and precepts. It is under this view that "Christ-centered preaching" has amounted in some circles to teaching only the doctrine of justification, regardless of the actual content of a Bible passage. No matter what commands, demands, or obligations are set forth in the text, the preacher's duty is to inform his hearers that it is Jesus alone who performs good works, since justification is through faith alone.

The answer to the question, however, is "No," since justification does not flow directly from justification. Rather, justification and sanctification are dual graces both of which flow from union with Christ in faith. We see this clearly in Paul's teaching that Christ "became to us wisdom from God, righteousness and sanctification and redemption" (1 Cor. 1:30). Each of these graces, including righteousness and sanctification, is located in Christ, rather than in one another. Our faith in Christ is passive as we receive a finished justification from him. Moreover, that same faith is active in embracing the call to holiness that Christ energizes through the ministry of the Holy Spirit (Eph. 1:19-20). This emphasis follows the apostolic pattern, in which sanctification is taught not by emphasizing justification but rather by emphasizing union with Christ and the sanctifying demands of the Holy Spirit (see 1 Cor. 6:15-17, Gal. 2:20, Eph. 4:21-24).

The Bible conceives of union with Christ in terms of a marriage between a bride and her groom, in which both justification and sanctification play essential roles. In our weddings, the bride comes to her husband dressed in the gleaming white of the bridal gown, just as the believer comes to Christ in the spotless radiance of his imputed righteousness, received through faith alone. But the bride does not just put on the dress: wearing the dress she comes to him, gives the groom her love, and commits to obey him so long as they both shall live. In fact, she presents herself to him, having carefully beautified herself for this moment. Similarly, in sanctification the believer cultivates the beauty of holiness to present to our Savior and Lord, who has justified us at so great a cost to himself. What a glorious marriage this is! Out of his amazing grace and love, God pledges himself to us: "So long as we both shall live, I will be your God." It is his justified and sanctified people who respond in a love of God's making within us: "So long as we both shall live, we will be your people."