“Union with Christ is right at the center of the Christian doctrine of salvation. The whole of our relationship with God can be summed up in such terms” (p.1).
All of that is certainly true, and yet when was the last time that you recall reading a book or hearing a sermon on this core doctrine of the Christian faith? In his book, The Hole in Our Holiness (reviewed here), Kevin DeYoung goes so far as to say,
“Union with Christ may be the most important doctrine you’ve never heard of.” (p.94)
Sadly, for far too many Christians those words ring true. But even for those who have heard of it and are at least somewhat familiar with this vitally important doctrine of the Christian faith, there are just not that many books and other resources on the subject that are both readily available and accessible to help us grow in our understanding of it.
Robert Letham’s book, Union With Christ, is a welcome exception. It is a very helpful, but not overwhelming volume (totaling a mere 141 pages!). It’s brevity adds to its helpfulness. It is a scholarly work, but not so academic as to be inaccessible to the lay person without an advanced theological degree. As the subtitle of the book makes clear, he makes his case plainly from Scripture, history (citing various ecumenical councils and controversies in the early church), and theology (citing a multitude of Reformed theologians from John Calvin to Charles Hodge).
The layout of the book is simple and easy to follow. Letham opens with a chapter showing how the basis of our union with Christ can be found in the opening chapters of the book of Genesis and its account of creation. Man was created in the image of God in order to be compatible with God. He then moves on in the second chapter to show that “[T]he basis of our union with Christ is Christ’s union with us in the incarnation” (p.21). In chapter three he discusses Pentecost and the Holy Spirit’s role in effecting or applying our union with Christ by grace through faith. Letham very helpfully and succinctly sums up the first three (3) chapters at the end of chapter 3 before moving on to the next section of the book.
In the final three (3) chapters of the book, Letham demonstrates the vital relationship that union with Christ has upon our standing before God with regard to our justification (representation – chapter 4), our sanctification (transformation – chapter 5), and, finally, our glorification at Christ’s return (resurrection – chapter 6). As he states on p.137, “Union with Christ is realized in its fullness at the resurrection itself, when we will be like Christ (1 John 3:1-2).”
If there is a weakness in the book, it may be in the somewhat parenthetical section on the doctrine of “theosis” (on p.91-102). Theosis (also known as deification) is a central tenet of the Eastern church’s doctrine of salvation, but is largely unheard of in the Western church. The terminology used can sometimes sound (especially to Western ears) as if the Creator-creature distinction were being blurred. I found Letham’s treatment of this subject here to be a bit confusing, even distracting. If you are reading through this book, and find this section to be too difficult, you could (in my humble opinion) easily skip over these pages and not miss a beat. It is interesting enough, but not in any way essential to his argument.
And on the very last page of the book, he makes a wonderful evangelistic appeal to the reader, lest anyone read this book and yet still not be united to Christ by faith. As Letham states there, this wonderful doctrine is much “more than an academic question. It is greater than life and death” (p.141).
This book covers a topic that is as important as it is neglected, and (Lord willing) many in our day may find it to be a helpful remedy for that neglect.