This will probably be the last of my thoughts on Calvin and the doctrine of union with Christ. That said, it seems that in keeping with Calvin’s mission to make the Institutes a summa pietas, he refuses to leave union with Christ in the ethereal, theological domain. For Calvin, union with Christ is an eminently practical doctrine, affecting the life of the Christian on a daily basis both devotionally and sacramentally. The Holy Spirit does not just bind the believer to Christ in the moment of conversion. Rather, union with Christ is the context in which the believer lives and moves and has his being. From the moment of justification onward, everything the believer does is in union with Christ, effected by the Holy Spirit’s working of faith within the heart of the believer.
J. Todd Billings points out that the pastoral import of Calvin’s doctrine of union with Christ is especially borne out when Calvin speaks of prayer. Citing section 3.20.1 of the Institutes, Billings remarks that “while union with Christ makes the riches of the Father available to believers, the Spirit enables believers to pray. Moreover, the Spirit enables believers to experience God as Abba, Father.” Thus, even an activity as basic to the Christian life as prayer is predicated on the Holy Spirit’s binding of the believer to Christ through faith. In Christ, the Father makes those joined to Christ His children through adoption, for “in him he opens to us the heavenly treasures that our whole faith may contemplate his beloved Son, our whole expectation depend upon him, and our whole hope cleave to and rest in him.”
Not only does prayer find its foundation in union with Christ, the sacraments of the Lord’s Supper and Baptism do as well. Calvin’s vocabulary regarding baptism is shot through with union and participation language. Important in baptism for Calvin is the initiatory nature of the rite, for in baptism one is identified with the Church and is also “engrafted in Christ” as one who is shown their “mortification in Christ, and their new life in him” that they may be “reckoned among God’s children.” In fact, Billings even points out that in Calvin’s work on baptism, he notes that the same duplex gratia conferred through union with Christ is conferred in baptism, for “the free pardon of sins and the imputation of righteousness are first promised us, and then the grace of the Holy Spirit to reform us to newness of life.” And yet, the duplex gratia of baptism points back to Christ, for “all the gifts of God proffered in baptism are found in Christ alone.” Thus, Calvin makes plain that baptism is tied to union with Christ, for in it the work of the Holy Spirit in uniting the believer to Christ through faith is signified and sealed to the believer.
Additionally, in Calvin’s doctrine of the Lord’s Supper, union with Christ appears as an illuminating theme. Calvin notes that “Godly souls can gather great assurance and delight from this Sacrament; in it they have a witness of our growth into one body with Christ such that whatever is his may be called ours.” The Supper, for Calvin, is an illustration of the benefits the believer receives by virtue of their union with Christ. It communicates to the believer that just as certainly as they eat the physical bread and drink the physical wine which physically nourishes their body, Christ, their spiritual sustenance, nourishes their soul. In the Lord’s Supper, Christ “offers himself with all his benefits to us, and we partake of him by faith.” Believers partake of the Lord’s Supper not so that they merely remember the sacrifice of Christ, but rather so that “when we see ourselves made partakers in it, we may assuredly conclude that the power of his life-giving death will be efficacious in us.” When the believer partakes of the Lord’s Supper, the believer in fact partakes of Christ, for in the Supper they are identified in Christ and in His “life-giving death.” In the Supper, as in Calvin’s doctrine of union with Christ more generally, the believer is made sure of this:
“This is the wonderful exchange which, out of his measureless benevolence, he has made with us; that, becoming Son of man with us, he has made us sons of God with him; that, by his descent to earth, he has prepared an ascent to heaven for us; that, by taking on our mortality, he has conferred his immortality upon us; that, accepting our weakness, he has strengthened us by his power; that, receiving our poverty unto himself, he has transferred his wealth to us; that, taking the weight of our iniquity upon himself (which oppressed us), he has clothed us with his righteousness.”
 J. Todd Billings, Calvin, Participation, and the Gift, 110.
 Billings, Calvin, Participation, and the Gift, 110 – 116.
 Calvin, Institutes, 3.20.1.
 Ibid., 4.15.5.
 Ibid., 4.15.1.
 Billings, Calvin, Participation, and the Gift, 121-122.
 Calvin, Institutes, 4.15.5.
 Ibid., 4.15.6.
 Ibid., 4.17.2.
 Ibid., 4.17.5.
 Ibid., 4.17.1.
 Ibid., 4.17.1. cf. also 4.17.12, in which Calvin says that “the Spirit alone causes us to possess Christ completely and have him dwelling in us.”
 Ibid., 4.17.2.