Just outside the front door of my home is a small ornamental tree that I planted last year. The tree is unusual looking, having a rounded evergreen canopy placed on top of a straight, branchless trunk. In fact, this plant is entirely unnatural, which is why it catches the eye compared to other plants around my home. Instead of being grown as a seedling, it was created by a skilled horticulturalist who grafted a bush-like dwarf pine onto a young white pine trunk. The graft between the two plants is still visible as a bulge near the top of the trunk. This bulge, however, is not just the scar tissue where the two plants were joined together. It is the living bond that ensures the ongoing exchange of fluids and nutrients between the trunk and branches of this tree.

The practice of grafting that was required to create this ornamental tree has been around for thousands of years and was commonplace in the Mediterranean world by the time the New Testament was written.1 Unlike the tree outside my front door, however, plants that were grafted in biblical times were produced primarily for agricultural and not ornamental purposes. In the early first century AD world, for instance, it was common to graft new shoots of grape onto a well-established vine or branches from a wild olive onto a domesticated trunk in an olive grove. As such, Paul’s analogy to grafting in Romans 11 would have been entirely familiar to his audience.

The practice of agricultural grafting allows for several advantages over traditional cultivation of plants from seeds. The most significant of these is the time-saving benefit, as most fruit-bearing species of vines or trees cultivated from seedlings take many years to grow before they become productive. Furthermore, not all varieties of fruit-bearing plants readily grow in a domesticated setting or can be propagated through seeds or cuttings, which means that they cannot be transplanted as seedlings to a hillside vineyard or olive grove. Grafting to a well-established vine or trunk not only assures that a transplanted shoot would more rapidly produce fruit, but also allow it to benefit from the hardiness of the vine or trunk (called the rootstock) to which it was grafted. In that way, common stressors such as lack of moisture, sensitivity to soil bacteria, or predation by certain insect pests can be alleviated by grafting.

The process of grafting the shoot or branch of one plant to the rootstock of another is both an art and a science. The art of grafting is seen in the many different ways that it can be performed, some that work better or worse with different types of plants. This challenge is compounded by the relative skill of the practitioner, who will inevitably find that his ability to make a successful graft improves significantly with time and practice. Through experience of success and failure he will learn to identify the variables that predict success, which include: the compatibility of the two plants being grafted; the proper alignment of the two plant tissues being grafted; the amount of pressure applied to the graft; and avoidance of water loss at the site of the graft.

The principles of proper grafting noted above are all intended to promote the cellular process that is occurring in a graft. For grafting to work, a layer of plant stem cells called the “cambium,” which lies just under the bark, must be exposed in both the branch and the rootstock. The cells of the cambium give rise to the vessels of a plant that are necessary for the flow of nutrients and water between the trunk and its branches. When properly aligned, the cells of the cambial layers will intermingle and meld to create a single, unified vascular system between the grafted branch and the trunk. Over time these stem cells will multiply and grow to create a strong, living bond of interwoven tissue that also serves as a permanent conduit through which the life of the trunk and its extensive root system are connected to the grafted branch.

Though members of the Mediterranean culture during the early New Testament were certainly not aware of the specific cellular details necessary for a grafted branch to survive and bear fruit, they would have no doubt recognized the imagery of an engrafted olive branch in Paul’s epistle to the Romans. In chapter 11 of this book, the Spirit of Christ directed the apostle to compare Gentile believers to wild olive branches that had been engrafted into the rootstock of a mature olive tree, which represents the covenant of grace that God has established with all of His elect people, starting with the chosen nation of Israel.

In this illustration, the physical graft uniting branches to the rootstock is not directly indicated; however, we can infer it by analogy from the words of verse 20-21: “Because of unbelief they [Jews] were broken off, and thou [Gentiles] standest by faith. Be not highminded, but fear. For if God spared not the natural branches, take heed lest he also spare not thee.”

From these verses we understand that the difference between the Jews who had rejected Christ and the elect Gentiles is faith. The “natural branches” were broken off because they lacked the bond of faith uniting them to the olive tree, while in contrast, the “wild branches” were made part of the tree through the bond of faith. Grafting of a believer into the covenant of grace is by faith alone, which therefore implies that faith can be represented as a graft between a branch and the rootstock in Paul’s analogy.

Before turning to the instructive features of this analogy, it is also worthwhile to reference Christ’s illustration in John 15. Similar to Paul’s illustration, Christ refers to believers as branches connected to a life-giving rootstock. In a slight variation on the illustration, however, Christ declared that He is the “vine” and believers the “branches.” Rather than focusing on the distinction between “natural branches” and “wild branches,” the emphasis here is on the life-giving power of the vine to which the branches are connected. No mention is made of a graft or bond here, but nonetheless we may again infer from the text the analogy to faith.

The necessary bond that unites branches to the vine is implied in Jesus’ illustration by His repeated use of the phrase “abide in” to describe the bond between branches and vine. The branches that abide in the vine will be fruitful because the life of the vine is in them (vv. 4,5). In contrast, the branches that abide not in the vine wither and are “cast forth” to be burned (v. 6). These verses make it plain that what differentiates between a live branch and a dead branch is its bond to—or “abiding in”—the vine. This parallel aspect between Christ’s illustration of the vine and Paul’s analogy of the grafted olive tree is striking and demonstrates the fact that what unites every believer to Christ is an abiding faith in Him.

Returning now to the value of this illustration, we can observe four aspects that are instructive in our understanding of faith as a graft. First among these is the fact that the graft is a living bond between an engrafted branch and its rootstock. Living grafts are dynamic. They grow with time and become increasingly strong and secure as the plant itself grows. And such is faith. It is a living, vibrant bond between the believer and Christ that continues to grow and strengthen under the preaching of God’s Word and through partaking in the sacraments as means of grace. Faith is not a static, inanimate bond like glue or tape. It is a dynamic bond between the believer and his Lord that enables the Christian to endure the storms of life that would threaten to tear him away from the Vine, ensuring that he will remain as a fruitful branch to the glory of God (John 15:8).

Second, the graft is the single conduit through which all the life of the rootstock flows to an engrafted branch. All of the water, minerals, and other nutrients absorbed by the roots of the vine or trunk flow to the branch through the vessels of the graft. No other tissue or part of the plant is necessary; the graft is the exclusive way that the life of the rootstock flows to the branch. So too is faith the exclusive instrument by which all the blessings of salvation in Christ are received and realized. No other instrument is used alongside of or in addition to faith to provide the blessings of salvation to a believer. Salvation in all its various parts, both objective and subjective, are received through faith alone.

Third, the graft is an inseparable bond in which the cells of the branch and the rootstock are so intermingled with one another that together they become one plant. If one were to cut out a slice of the graft and inspect it under a microscope, it would be impossible to distinguish which cells are from the branch and which are from the trunk. They would appear to be one, single unit in the same way that a natural branch is connected at the cellular level to its trunk. This is a remarkable analogy to the result of faith, which is the union of the believer to Christ. We become one in Him, who is our Righteousness and Head. This truth is emphasized throughout Paul’s epistles, which repeatedly (more than 70 times!) use the phrase “in Christ” to describe the inseparable union between the believer and his Lord. Though each of us is a unique and separate branch grafted to Christ for the glory of God, we are one organism through the gift of faith that unites us to Him.

As a side-note here, there is a remarkable feature of Paul’s analogy that clearly deviates from the illustration of an actual graft and would certainly have struck his audience as odd, too. In Romans 11:23-24, Paul speaks of the re-grafting of the dead, native branches of Israel back on to the olive tree from which they were broken off. Any gardener familiar with grafting would know, however, that this is impossible. Once a branch is dead, it can no longer be grafted because a living cambium is required from both the branch and the rootstock for a graft to form. Without the contribution of cells from both sources, a bond between the two cannot be established.

In Paul’s inspired deviation from the natural world, we see the wondrously sovereign and unilateral nature of faith as a gracious gift from God to which we contribute nothing. The actual bond of faith is unlike a biological graft because it is established solely from the living vine and not from the branches. This is so true that even a dead branch destined for the burn pile, which all of us are by nature, can be grafted into Christ. As the fully divine second person of the Trinity, Christ alone is the source of the gracious gift of faith that unites us to Him.

The fourth and last aspect of a graft that is instructive for us is that it is a visible bond between the two parts of the grafted plant. In this way a graft is very much like a scar that tells the history of the plant. It says that this plant did not occur naturally but was formed as the result of a violent cutting that preceded the union of its two parts. Both branch and rootstock were severed that they could be one, leaving behind an ever-growing bulge testifying to this history and the strength of the union that resulted from it.

Such is the nature of the true faith that unites a believer to Christ. It is a visible “scar” in the life of the believer that testifies to the death of his old man of sin and new life that now flows to him from Christ. And in its visibility, it boldly proclaims that the only way to union with Christ is through the violent shedding of His blood on the cross for the sins of His elect people. So, believer, bear this visible scar openly and thankfully in your life, acknowledging that it is your union to our Lord through which all of the blessings of His saving grace flow!

“I am crucified with Christ: nevertheless I live; yet not I, but Christ liveth in me: and the life which I now live in the flesh I live by the faith of the Son of God, who loved me, and gave himself for me” (Gal. 2:20).

1 Ken Mudge, Jules Janick, Steven Scofield, and Eliezner Goldschmidt. “A History of Grafting.” Horticultural Reviews, volume 35. Ed. Jules Janick. (John Wiley & Sons, Inc., 2009).