John Calvin situates our “mystical union” with Christ with “the highest degree of importance.” By our union with Christ, we experience a “fellowship of righteousness.” This is why our imputed righteousness is not some remote thing that comes to us. We experience God’s righteousness in a personal way. We have it in mystical union with Christ.
Here are Calvin’s words (the fuller context is his interaction with Osiander):
“I confess that we are deprived of this utterly incomparable good until Christ is made ours. Therefore, that joining of Head and members, that indwelling of Christ in our hearts—in short, that mystical union—are accorded by us the highest degree of importance, so that Christ, having been made ours, makes us sharers with him in the gifts with which he has been endowed. We do not, therefore, contemplate him outside ourselves from afar in order that his righteousness may be imputed to us but because we put on Christ and are engrafted into his body—in short, because he deigns to make us one with him. For this reason, we glory that we have fellowship of righteousness with him” (Inst. 3.11.10, pp. 736-37).
Here are a couple thoughts.
Calvin’s View of Salvation Is not Remote, or Impersonal
Sometimes the doctrine of justification by faith can feel mechanical, cold. Christ’s alien righteousness is imputed to those who have faith. And that sounds like a legal transaction written with a pen on paper, not by the spirit on the heart.
But Christ has come to us by a “mystical union.” We don’t “contemplate him outside ourselves from afar.” We share “with him in the gifts” that God has bestowed upon him. In Christ, they are ours.
Calvin’s View of Imputation Overlaps with Union
Calvin clearly argues that Christ’s righteousness is imputed to those who have faith. But he also teaches that faith (by the Spirit) unites us to Christ. And in this union, we have a “fellowship of righteousness” with Christ. By associating imputation and union, Calvin underscores the importance of our uniting faith in Christ by the Spirit.
With such a limited study of Calvin, I don’t want to overstate the case. I did not see Calvin saying “Christ imputes his righteousness through the union.” Instead, Calvin sees our union with Christ in association with our imputation. Union brings us into fellowship with Christ and his righteousness.
While others can specify the exact relationship between union and imputation, I think it’s important to affirm with Calvin these two things: Christ is close to us and we have a “fellowship of righteousness with him.”