11:15 若他们被丢弃，天下就得与神和好，11:16 所献的新面若是圣洁，全团也就圣洁了；
11:21 神既不爱惜原来的枝子，也必不爱惜你。11:22 可见神的恩慈和严厉：
11:24 你是从那天生的野橄榄上砍下来的，11:25 弟兄们，我不愿意你们不知道这奥秘
11:29 因为神的恩赐和选召是没有后悔的。11:30 你们从前不顺服神，
11:32 因为神将众人都圈在不顺服之中，特意要怜恤众人。11:33 深哉，神丰富的智慧和知识！
11:34 “谁知道主的心？11:36 因为万有都是本于他，倚靠他，归于他。
"Chosen by grace" does not mean that God choses arbitrarily, but rather choses those who put their faith in Christ. This is not by works, for the Bible does not categorize "believing" as a work (罗马书４：４，５) On the other hand, if one truly believes, there should be outworkings to one's faith - outworkings that are so inevitable that one might even measure their salvation status by them. But what is the difference between these outworkings of faith and the mistake that these Jews made in seeking righteousness by works? The difference is that though we have outworkings of our faith, we do not put our faith in the applications of our faith. Rather, we put our faith in the atoning work of Christ. We do not put our faith in such things as Baptism and obedience to Christ's commands to save us. Though these are applications of our faith.
But what are they being joined to and cut off from? Is it salvation? I don't think so. It seems to me that Paul is referring to the outward manifestation of God's people. For example, before Christendom, the outward manifestation of God's people was the nation of Israel, or the "Jews". They represented God's people. But these people were not automatically saved just because they were born Jewish, or because they had been circumcised.
After Christ, God's people were changed from Judaism to Christianity. It changed from the Jewish nation to Christendom. But Christendom was not a new tree. It is in fact the same old tree. Christianity is the "true" Judaism. Judaism as the unbelieving Jews perceive it is contrary to Christianity. Thus they have cut themselves off from the true Judaism, which is Christianity. And if they come to faith in Christ, they can join themselves back on to the true Judaism.
When a Jew or Gentile identify with Christendom, by claiming faith in Christ and getting baptized, that may not necessarily mean that they have been "saved" (or "justified"), but rather that they can be called and treated as a Christian. But the requirement for salvation goes beyond outward things. It requires an inward faith that is confident, enduring and application-oriented. And while many "play" Christianity on an outward level, it often takes a while for a Christian to travel through the outward "nominal" stage before their faith is on the level of a conviction. And this is a basis for fear.
Paul speaks of the benefits of Israel's fall. But why was it necessary for branches to be broken off? Wouldn't it have been even better if the vast majority of Jews had accepted the gospel and then spread it to the Gentiles? It seems from the book of Acts, much of the motivation and opportunity of spreading the gospel to the Gentiles was really born of the hostility the Jews had against the gospel. Persecution against Christians by the Jews helped to spread the gospel to the Gentiles. (使徒行传１３：４６ Then Paul and Barnabas answered them boldly: "We had to speak the word of God to you first. Since you reject it and do not consider yourselves worthy of eternal life, we now turn to the Gentiles.) Just as the Jew's murder of Jesus brought salvation to the world, so even their rejection of the gospel and persecution of Christians caused the gospel to be spread. Of course, this doesn't justify their behavior, for which they will be held accountable. But it shows that God can use us despite our sinfulness. They were chosen for such a purpose, acting appropriately for the role. But the story is not over. For their role is not finished. In the end they (as a category) will accept the Messiah."Examine yourselves to see whether you are in the faith; test yourselves. Do you not realize that Christ Jesus is in you-- unless, of course, you fail the test?" 歌林多后书１３：５ (niv)
What would have happened if the Jews had not acted with hostility against
the gospel message? Perhaps things would not have turned out as well as
they did. As Job asks "Who has known the mind of the Lord? Or who
has been his counselor?" On the other hand, Paul writes:
"For who hath known the mind of the Lord, that he may instruct him? but we have the mind of Christ." 歌林多前书２：１６ So perhaps we can understand these things.
vs 32 "have mercy on them all" (Categorically not individually)