Why does Paul insist upon the imputed active obedience of Christ in our justification? Why is this necessary aside from the fact that the Scriptures teach its necessity? The answer lies in the nature of our justification. We must recognize that the ground of our justification is not our sanctification, or the transformative aspect of our union with Christ. To base our justification in our sanctification is to change the judicial ground from the work of Christ to the work of the believer. The good works of the believer, even those that are the result of the sanctifying power of the Holy Spirit, are at the end of the day imperfect. . . .

It is only the obedience of Christ, therefore, that can be the ground of our justification, not only the obedience that he offered in his vicarious suffering throughout his entire earthly ministry, his passive obedience, but also his perfect law-keeping that he offered on our behalf to his Father, his active obedience.

In terms of union with Christ and justification, Berkhof therefore explains that “justification is always a declaration of God, not on the basis of an existing condition, but on that of a gracious imputation-a declaration which is not in harmony with the existing condition of the sinner. The judicial ground for all the special grace which we receive lies in the fact that the righteousness of Christ is freely imputed to us.” What we must realize, then, is that the ground of our redemption is the work of Christ; correlatively, we should also recognize that the ground of our sanctification is our justification. In other words, apart from the legal-forensic work of Christ, received by imputation through faith, there is no transformative work of the Holy Spirit. Or, using the title of John Murray’s famous book, apart from redemption accomplished, there can be no redemption applied (see WCF 11.3; Larger Catechism, Q/A 70). (John Fesko, “Toward A More Perfect Union?” Modern Reformation)

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