The apostle Paul, in these verses, gives nine unassailable grounds for Israels future restoration.
The goodness of God
We are called upon to "Behold the goodness and severity of God" (v.22). Israel is a testimony to Gods severity in the present day. The reason for the severity, seen in the branches being broken off (v.20), was unbelief. The crowning act of unbelief was when Messiah was crucified. What severity there was on that nation! In AD 70 the streets of Jerusalem flowed with blood: 1,100,000 Jews perished. This was predicted in Daniel 9. The Lord Jesus Christ spoke of it both in parables and in the Olivet discourse. There were weary feet and heavy hearts. Behold, says the apostle, the severity of Lord.
The goodness of God has been shown in that the gospel has been preached to the Gentiles. Indeed, Paul was then the apostle to the Gentiles. However, the Gentiles have not continued in the goodness of God. Now, so much of Christendom is given over to atheism, humanism, and secularism. Christendom is now a great force. Influential, powerful, political emissaries of Satan are in Christendom now: these are the birds of Matthew 13, which lodged in the branches of the tree that grew from the mustard seed. Christendom is now full of obsolete Judaism and corrupt paganism. This is an unholy mixture and we now see the harlot church of Revelation 17 taking shape. Under the severity of God it will experience judgment in a terrible way for it is a solemn matter to despise Gods goodness and kindness. Israel will not always abide in unbelief. In Gods goodness Israel will be grafted in again (v.23).
The power of God
The second unassailable ground for Israels future restoration is Gods power. He had not spared "the natural branches" (v.21) but v.23 indicates that "God is able to graff them in again". The Jew is now loved by God: though he is under Gods severity God has both the desire and ability to bless.
The faithfulness of God
Further, God will perform His word (v.24). Israel is the good olive tree; Gentiles are the wild olive tree. Just as it is contrary to nature to graft that which is wild by nature into a good olive tree so it was no small matter when God brought into Abrahams blessing the Gentiles who were strangers to the covenants of promise. The restoration of Israel will be simpler for it will be according to nature.
The mystery now revealed
Fourth, in v.25, Israel will be restored according to New Testament revelation. The mystery to which the apostle refers is that Israels blindness is neither total nor final. "Blindness in part" is not partial blindness, for Israel as a nation is totally blind. "In part" is therefore not in terms of degree but of extent: this blindness did not affect the whole nation but only part of it for there is now a remnant according to the election of grace. Paul was himself a proof that that blindness is not total. Further, that blindness is not final for it is "until the fulness of the Gentiles be come in". Let this word "until" ring in the ears of those who say there is no future for Israel. The "fulness of the Gentiles" refers to the full complement of the saved called out of the Gentiles. Souls are still being saved and will yet be. Gentiles should not assume, on the ground of their own wisdom, that it is due to them that they have received what the Jews refused. To do so would be conceit.
Next, the past prophetic word assures us of Israels future (v.26). The apostle states that "all Israel shall be saved", and cites Isaiah 59.20. Whether the deliverer comes "to" Sion, "for the sake of" Sion (Septuagint), or "out of Sion" (Rom 11.26), the point is that the Redeemer shall come. It is literal Sion that is referred to. From Sion He shall send the rod of His power in the day when He turns away ungodliness from Jacob. This will be Israel after divine dealings with the nation as a whole. Now, from the Jews He is saving only a remnant; Paul was one of them. The remnant is small but national deliverance shall mean that all Israel shall be saved. The Jacob character of Israel will be removed.
Israels covenant relationship with God
The sixth reason given by the apostle for the future of the nation of Israel is its covenant relationship with God (v.27). Reference is made to Isaiah 59.21. In Isaiah the reference is to the new covenant of Jeremiah 31 (see Jer 31.34.) The language of Romans 11 is to be noted: it is "my covenant unto them". This is unusual: it might have been expected that it would have been referred to as "my covenant with them", but it is "unto them". The New Covenant is not between two parties as was the covenant at Sinai where blessing was contingent upon obedience: in the New Covenant God alone has responsibility. The covenant was not just made but consummated and blessings are therefore guaranteed. There is a plenary and perpetual forgiveness beautifully referred to in Daniel 9.24.
Seventh, election assures blessing. The Jews are hostile to the gospel now. 1 Thessalonians 2.16 speaks of the Jews "Forbidding us to speak to the Gentiles that they might be saved". Nevertheless they are beloved for "the fathers sakes" (Rom 11.28).
Election is referred to three times in Romans 11 (vv.5,7,28). It is important to observe that when reference is made to the election of this day of grace, it is individual for Jews who believe: "there is a remnant according to the election of grace" (v.5) and, "the election hath obtained it" (v.7). In v.28 however - "as touching the election they are beloved for the fathers sakes" - the reference is to election nationally. God cannot but be faithful to his electing love which assures Israels restoration. To say there is no future for Israel attacks Gods faithfulness and electing choice. In Deuteronomy 7.6-8 that nation was chosen to be a special people unto Himself. Nothing they do is either unknown to Him or changes the choice of His love.
The immutability of God
Gods immutability is the next factor that assures Israels future (v.29). Men change their minds but not God. God has given gifts to Israel through the promise to Abram of a nation, seed and land and called that nation to a glorious inheritance. Israel received gifts on the principle of grace, and calling on the principle of promise. God has by no means changed His mind: grace is grace; promise is promise; faithfulness is faithfulness. One might as well teach a falling away doctrine in this present day as teach that there is no future for Israel. The Jewish nation cannot be destroyed.
The mercy of God
Lastly in this chapter a future for Israel is assured on the ground of Gods mercy. "For as ye in times past have not believed God, yet have now obtained mercy through their unbelief: Even so have these also now not believed, that through your mercy they also may obtain mercy" (vv.30-31). Through Gods mercy to the Gentiles the nation will obtain mercy.
A doxology closes both the chapter and the dispensational section of the epistle. Paul acknowledges that his own wisdom is unable to comprehend Gods mind. It is arrogance to discuss what we cannot understand. His ways are unfathomable, unteachable, and untraceable. God is indebted to nobody for advice (vv.34-35). If anyone can show that God owes him for counsel or advice he will be recompensed, but in fact God owes no one (v.36). He knew the end from beginning. God planned, God executes, and God accomplishes His own purpose for His own glory. God is the source, means, and end of His counsels and purpose.