If some of the branches have been broken off, and you, though a wild olive shoot, have been grafted in among the others and now share in the nourishing sap from the olive root, do not consider yourself to be superior to those other branches. If you do, consider this: You do not support the root, but the root supports you. You will say then, “Branches were broken off so that I could be grafted in.” Granted. But they were broken off because of unbelief, and you stand by faith. Do not be arrogant, but tremble. For if God did not spare the natural branches, he will not spare you either.
Moving into Paul’s next point, we have an olive tree being used as a metaphor for judgment and hope. In these first several verses, Paul is addressing Gentiles who are likened to a wild olive branch that has been grafted into a cultured olive tree. The grafting has taken place so that these wild branches can take the place of the original branches that were broken off from the tree.
The tree represents the Israel of God, and when those new branches (Gentiles) are grafted into the tree, it is the tree that supports and nourishes these new branches and not the other way around, thus the new braches must not think themselves superior to the old ones (17-18). The old branches were torn away from the tree by their unbelief; the new branches were grafted in by their faith (19-20). Now comes the warning: If those new branches allow themselves to become arrogant and superior, they too can be broken off and replaced (21).
Consider therefore the kindness and sternness of God: sternness to those who fell, but kindness to you, provided that you continue in his kindness. Otherwise, you also will be cut off. And if they do not persist in unbelief, they will be grafted in, for God is able to graft them in again. After all, if you were cut out of an olive tree that is wild by nature, and contrary to nature were grafted into a cultivated olive tree, how much more readily will these, the natural branches, be grafted into their own olive tree!
The warning for Gentiles continues, and the message of hope for the Jews is given in these verses. If the unbelief of hardened Israel does not continue, they will be welcomed back to the tree of faith, and it will be easier to graft the branch back to the tree from which it came, then it was to graft in the wild branches. What is the point?
To the Gentiles, Paul is warning them that they must continue in their faith with humility before God, and to the Jews Paul is saying that they are welcome to come home in faith whenever they choose to do so. Essentially, this is what he has been teaching throughout this larger unit of Romans and this metaphor is being used to begin to sum things up as we near the close of the unit. In the next section, verses 25-32, he will drop the metaphor and tell his readers in plain language about God’s Kingdom strategy. It is very important that we bear this in mind when we study it, for if we don’t, we are likely to come up with all sorts of erroneous conclusions.