For if the firstfruit is holy, the lump is also holy; and if the root is holy, so are the branches.
Paul had not given up on saving some of his fellow countrymen according to the flesh (Romans 11:14). He apparently knew he would face some pushback from the Gentiles in his efforts to try to save some of the Jewish people.
So, beginning in Romans 11:11, he started identifying and tearing down some arrogance that had been demonstrated among some Gentile Christians.
Here, in Romans 11:16, Paul lays down a principle that will be important going forward in this chapter.
The Firstfruit and the Root.
Whatever the “firstfruit” and the “root” are, they must refer to the same thing - because Paul uses two different examples to make the same point.
The illustration is taken from Numbers 15:17-21. When God brought Israel into the land to eat the bread of the land they were to offer unto him an offering of that bread. This firstfruit of the bread not only guaranteed that God would supply the rest for them, it (as it were) released the rest for ordinary consumption. The dedication of the part implied God’s recognition of the whole. The “firstfruit” stands for the patriarchs as the recipients of the promises and their descendants (physical but faithful if they were to be regarded as real heirs). - McGuiggan, Romans, 317
If the patriarchs (Abraham, Isaac, and Jacob) and the promises God made to them are indeed the “firstfruit” and the “root,” then Paul’s point is that those who are connected to them and the promises God made are “holy.”
God used the Jewish nation to bring the Messiah into the world, and even their rejection of the gospel opened doors for the Gentiles to receive the gospel and enjoy the blessings of God’s promises (Galatians 3).
Paul is walking a line between two extremes.
One extreme was to think too highly of the physical nation of Israel - something many of the Jewish people were guilty of doing, and even some people today.
The other extreme was to think too little of the physical nation of Israel, to think God no longer even cared about them - something some of the Gentile Christians were apparently thinking.
While both of these extremes included bits of the truth in their thinking, neither of these extremes was actually correct.
The metaphors in verse 16 are simple on the surface but are also very profound. Israel was God’s chosen people; and, in the face of rampant anti-Semiticism in society, Gentile Christians in the church at Rome had to reject such slander and appreciate their Jewish connections. They had to have the proper attitude toward Jews, despite their overall failure to accept the gospel. How Paul envisioned their relationship with the Jews is vividly laid out in 11:17-24 by the allegory of the olive tree. - Pollard, Truth for Today Commentary, 393-394
As Paul is about to begin warning the Gentile Christians not to think of themselves more highly than they should in comparison to the Jews, he reminds them - “You wouldn’t even be in this position if it wasn’t for God using the physical nation of Israel!”
Amen
Jesus was a Jew, the Apostles were all Jews, Paul went to the Synagogues also to preach to the Jews and Gentiles.
In the early years of the Church, at least until the Jerusalem Temple was destroyed in 70AD, most converts to Christianity were Jews. The Old Covenant scriptures that spoke about Christ, were read every week in the Jewish Synagogue on the Sabbath Day, where both Christian Jews and non-Christian Jews worshiped the same God, in the same place, at the same time. There was a natural relationship between those in the New Covenant and those in the Old Covenant, and no reason they should not worship God in the same place at the same time- the Jewish synagogue, on the Sabbath.
Paul also worshiped God in the synagogue. (Acts 13:14-15, 13:42, 17:1-17, 18:4-19) Ironically, it was because Christians worshiped in the synagogue with unconverted Jews, that the unconverted Paul (called Saul at the time) had been able to easily round them up to cast them into prison. (Acts 22:19, 26:11)
Later, as Paul and Barnabas travelled to the gentiles, they frequently preached on the Sabbath, in the synagogues, to both Jews and Greeks. This meant that most gentile Christians were actually converted in the synagogue, and they continued to go to the synagogue after they were converted. (Acts 14:1, 19:8)
God expects both Jew and gentile to become Spiritual Jews:
For he is not a Jew, which is one outwardly; neither is that circumcision, which is outward in the flesh: But he is a Jew, which is one inwardly; and circumcision is that of the heart, in the spirit, and not in the letter; whose praise is not of men, but of God.
(Rom 2:28-29)