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.
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:
We affirm that both justification and sanctification are distinct, necessary, inseparable and simultaneous graces of union with Christ through faith.
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).