While reading Clement of Alexandria during a recent church service, I happened to read what good ole Clement thought of Romans 11, and, SURPRISE SURPRISE, he saw the language of engrafting as being very helpful too. I know, WHAT ARE THE ODDS!
This is a pretty extensive quote [Clement's Stromata/The Carpets, Book 6, Chapter 15], so I am going to break it down, and mansplain this one:
Different modes of engrafting illustrative of different kinds of conversion. They say that engrafting is effected in four modes: one, that in which the graft must be fitted in between the wood and the bark; resembling the way in which we instruct plain people belonging to the Gentiles, who receive the word superficially.
First thing I would like to note by the first mode is that Clement makes use of the biblical category of GENTILE. Our “conversion” to the faith is not the, ahem, one way to come to know the One True God that the prophets preached. In other words, the place where we Gentiles stands is one of incorporation.
Another is, when the wood is cleft, and there is inserted in it the cultivated branch. And this applies to the case of those who have studied philosophy; for on cutting through their dogmas, the acknowledgment of the truth is produced in them. So also in the case of the Jews, by opening up the Old Testament, the new and noble plant of the olive is inserted.
The second mode is enlightenment, and this is primarily the place of where the Jews, God’s chosen ones stand. Why do I say this? Because Clement argues that the philosophers stole or borrowed their best ideas (monotheism, ethics that line up with The Law), from the Jews. On the hierarchy of philosophers, the ancient Hebrews are at the very top of the pyramid for Clement. While the language of enlightment brings its own set of problem, I think a limited use in this instance is valuable.
The third mode of engrafting applies to rustics and heretics, who are brought by force to the truth. For after smoothing off both suckers with a sharp pruning-hook, till the pith is laid bare, but not wounded, they are bound together.
Of the four modes, the third one is the most troubling for me. Even if Clement means in a not-so-PC fashion that verbal confrontation of heretics and pagans, I mean, rustics, will mean arrival at truth, there is something dominionist and violent about this approach to Christianity and other religions. A fellow Alexandrian, Cyril, years later, may have taken these words to heart, and lead mobs against Egyptian Jews. Of course, that would mean overlooking Clement’s second mode for engrafting.
And the fourth is that form of engrafting called budding. For a bud (eye) is cut out of a trunk of a good sort, a circle being drawn round in the bark along with it, of the size of the palm. Then the trunk is stripped, to suit the eye, over an equal circumference. And so the graft is inserted, tied round, and daubed with clay, the bud being kept uninjured and unstained. This is the style of gnostic teaching, which is capable of looking into things themselves. This mode is, in truth, of most service in the case of cultivated trees. And “the engrafting into the good olive” mentioned by the apostle, may be [engrafting into] Christ Himself; the uncultivated and unbelieving nature being transplanted into Christ–that is, in the case of those who believe in Christ. But it is better [to understand it] of the engrafting  of each one’s faith in the soul itself. For also the Holy Spirit is thus somehow transplanted by distribution, according to the circumscribed capacity of each one, but without being circumscribed.
Clement’s last mode is more about sanctification and perfection, what he referred to as assimilation, or the believer (gnostic) is participating in the life of Christ by the power of the Holy Spirit. This requires a Trinitarian understanding of personhood: an idea that all humanity has the potential to become involved in the divine life of YHWH.
I am just still trying to sort all of this out, but I think the implications of Clement’s use of engrafting are 75% helpful when it comes to discussing other religions, and possibly even mission work. For Gentiles, our vocation is to approach other Gentiles, as Gentiles, in honesty, and not hiding (or denying this fact). To this effect, we can have a conversation about religion not on our terms, but on possibly others’ terms, and affirm the uniqueness of their experience, all the while, Christians can present the Good News of the Resurrection, and the truth about the person Christ Jesus. As for the problematic third mode, I would revise the budding language, and rather than aim it at the “rustics” as city slicker Clement would have us, but rather a verbal confrontation towards apostates and heretical Christians. There’s good precedent set for this by the apostle Paul in his letters to the Corinthians. So, the difference would be the “budding” as an interior critique that takes place inside the Body of Christ.
Wherefore also, though the wild olive be wild, it crowns the Olympic victors.