Union with Christ was integral in the soteriology of the Reformers, and especially that of Calvin. As Marcus Peter Johnson notes in One With Christ, “when Calvin wrote of being united to Christ, he meant that believers are personally joined to the living, incarnate, crucified, resurrected Jesus...this union with Christ, which Calvin described in strikingly graphic and intimate terms, constituted for him the very essence of salvation. To be saved by Christ, Calvin kept insisting, means to be included in the person of Christ. That is what salvation is” (Johnson 12, emphasis original). And it wasn't just a heady doctrine, either; for the Reformers, union with Christ had multifaceted implications for the life of the believer and the life of the Church. Many, myself included, can attest to a fundamental change in personal spirituality as well as approach to life and ministry upon discovering and plunging the depths of the doctrine of union with Christ. I've therefore been delighted by the steady stream of excellent books on the topic in recent years (e.g. R. Letham, J. Billings, M. Johnson, C. Campbell, G. Macaskill, etc), many written from a Reformed perspective. Naturally, I was very eager to read the latest offering from Robert Peterson, Salvation Applied by the Spirit: Union with Christ.
Structurally this book is similar to the volumes in Crossway's Theology in Community series, with a bulk of the book (twenty chapters in this case) providing a sweeping overview of what the entire Bible has to say about the topic. Then a chapter is devoted to a biblical theology of union with Christ, followed by seven chapters treating the doctrine from a systematic perspective. Because union with Christ is most often dealt with from the Pauline epistles and to a lesser extent the Johannine corpus, naturally what makes Peterson's contribution most unique and valuable are the insights he provides from the rest of the canon. The recent monograph by G. Macaskill does consider the entire NT, but I'm not aware of any other book that examines union with Christ in the OT. This makes Chapter 1, “Foundations in the Old Testament,” especially interesting. The primary conceptual criteria used by Peterson to determine what qualifies as an OT foreshadowing of union with Christ are the concepts of identification, incorporation, and participation (drawn from C. Campbell's 2012 Paul and Union with Christ: An Exegetical and Theological Study). Peterson expounds upon identification as God's covenantal presence with his people, incorporation as membership in God's people, and participation as sharing in the covenantal story.
The next two chapters continue to draw on C. Campbell's tripartite definition. Concerning the Synoptic Gospels, Peterson develops the concept of identification in Jesus as Immanuel and Bridegroom, incorporation through Jesus as covenant Mediator par excellence, and participation in the story of Jesus. The doctrine of union with Christ is not present in the Synoptics, but these books establish the theological and redemptive-historical foundations for union; they “point to the actual establishing of that which believers are united to” (34). Regarding the foundation laid in Acts, Peterson addresses identification in the ministry of the Holy Spirit and Paul's conversion, incorporation in the rite of baptism, and participation in the repetition of Jesus's story and Luke's use of Isaiah's “suffering servant.”
With Chapter 4, we enter into the heart of the New Testament's treatment of union with Christ with the Fourth Gospel. Here, Peterson focuses on five passages: Jesus as the bread of life (John 6); mutual indwelling of the Father and the Son (John 10); mutual indwelling of the Father and the Son, and the Father and the Son and believers (John 14); Jesus as the Vine with believers as the branches (John 15); and the mutual indwelling of the Father and the Son and the Son and believers (John 17). The next ten chapters are dedicated to the Pauline corpus, going book-by-book to explore what Paul wrote about union with Christ, which is present in all of his biblical writings except Titus. Subsequently, Peterson takes two chapters to summarize union with Christ in Paul's letters, looking at the themes of union in greetings, “in Christ” language, being “in” the Father and the Son, participation in Jesus's narrative, the body of Christ, temple, marriage, new clothing, filled to the fullness, and indwelling. Part 1 concludes with four chapters on the rest of the NT, looking at Hebrews 3:14, the Petrine epistles, 1 John, and Revelation.
Part 2, Union with Christ in Theology, begins with a chapter looking at the unfolding of the topic in the biblical story, focusing on six stages in the biblical narrative: union and eternity past, union and creation, union and the fall, union and the incarnation, union and Christ's work, and union and the new creation. The next three chapters are devoted to the Holy Spirit, with chapters 22 and 23 setting the foundation for His pivotal role in applying salvation by uniting believers to Christ. Chapter 22 sets forth the Holy Spirit's personality and His deity, and Chapter 23 examines His works besides union with Christ (in creation, Scripture, the world, the apostles, and Jesus). Peterson devotes a bit of extra attention to the work of the Spirit in Jesus, beginning with a look at OT predictions and then addressing the Spirit's work in Jesus's conception, earthly ministry, death, and resurrection, concluding with Jesus's baptism of the Church with the Spirit.
With two chapters of foundation in place, Chapter 24 goes on to cover the most important work of the Holy Spirit in the realm of salvation: union with Christ. Here Peterson deals with three aspects of Paul's theology of the Spirit's role in uniting the believer to Christ: 1) the Spirit is the bond of union with Christ; 2) those who do not have the Holy Spirit do not belong to Christ; and 3) the Spirit brings about aspects of salvation that occur in union with Christ (regeneration, justification, adoption, sanctification, preservation, and glorification). Next, Peterson devotes a chapter to the Christ of union with Christ. This is fitting since “[i]t is too common to focus on the benefits of union with Christ and lose sight of the Christ to whom we are united” (348). The final chapters focus on the implications of union with Christ on the church, the sacraments, and Christian living.
Salvation Applied by the Spirit is possibly the most comprehensive book on union with Christ, providing an overview of what the entire Bible from beginning to end says about the topic, then giving a biblical theology of the doctrine, subsequently examining it in systematic perspective, and finally addressing practical implications in the life of the believer and the Church. I'm not aware of any other book that covers this crucial doctrine from all these perspectives. And despite its length, Salvation Applied by the Spirit is written at a lay-accessible level and provides an excellent introductory overview of union with Christ for the thinking Christian.
However, for more advanced readers who have studied this doctrine and have somewhat kept up with the literature, Peterson's volume might be underwhelming. In part the book can't be faulted for this, for depth must inevitably sacrificed when such breadth is pursued in one volume. Therefore it is natural that there would generally not be profound exegesis or theological insight, but more of a surface-level overview. But one very noticeable characteristic that I find to be a shortcoming of this work from an academic perspective is the heavy reliance on the work of others. Again, on one hand, this is fine because union with Christ is such a complex topic. Without summarizing someone else's conclusions it would take 100 pages just to define union with Christ. Using C. Campbell's definition as a foundation is legitimate. Yet the profuse quoting, often in block quotes, and with said block quotes sometimes taking up half a page, makes the book at times feel not like much of an original contribution.
The above criticism is only from an academic perspective; excessive quoting is common in popular-level books, and so, depending on the audience, it might not be seen as a shortcoming at all. So while readers more familiar with the doctrine of union with Christ probably wouldn't miss much by skipping this book, those who have not really studied this doctrine would find Salvation by the Spirit an extremely eye-opening, enjoyable, and fruitful read. This book is an excellent introduction to union with Christ from biblical, theological, and practical perspectives.
Disclosure of Material Connection: I received this book free from the publisher. I was not required to write a positive review. The opinions I have expressed are my own. I am disclosing this in accordance with the Federal Trade Commission's 16 CFR, Part 255: "Guides Concerning the Use of Endorsements and Testimonials in Advertising.
Jennifer Guo counts beans by day and eats books by night. She is passionate about the gospel and loves biblical and theological studies. She also loves the arts and is part of a performing arts ministry that uses a variety of mediums to communicate the gospel, God’s heart, and His design for sexuality, relationships, and marriage. Jennifer also loves running and cooking (and not because running allows her to eat more). You can follow her @JenniferGuo and read more of her thoughts at Jennifer Guo.