“For if thou wert cut out of the olive tree which is wild by nature, and were graffed contrary to nature into a good olive true; how much more shall these, which be the natural branches, be graffed into their own olive tree?”
Here we see Paul continuing using the olive tree as his illustration.  This olive tree is Abraham as its root.  Some its branches have been cut off–the nation of Israel, as such, has been rejected; and God has grafted in Gentiles.

“For if thou.”
Literally:  “For if you.”  You, who are Gentiles.  If wild branches were grafted into the good olive tree, as the Gentiles were grafted into the spiritual stock of Abraham, how much more likely is it that the natural branches, the Jews, shall again be grafted again into their own olive tree, the seed of Abraham to which they belong by nature.

“wert cut out of the olive tree”
Literally: “If you were cut out of the natural order wild olive {tree}.”  Or, “If you were of  the cutting of the wild olive tree.”  Were cut off.

            “which is wild by nature”
            Literally: “By nature.”  Literally:  “according to nature.”

Paul’s argument here is that it is in itself as difficult a thing to reclaim them, and change them from opposition to God, to friendship with Him, as it was difficult or impossible to reclaim and make fruitful the wild olive tree.

            “and were graffed contrary to nature”
            Literally: “Against nature were grafted into a good olive{tree}.

           CONTRARY TO NATURE (Grk.–para phusin)–Literally:  “against nature.”  This is the gist of Paul’s argument.  Paul is referring to the power of God to do what is contrary to natural processes.  God put the wild olive (Gentile) into the good olive tree (Israel) and (contrary to nature) made the wild olive become the good olive; the garden olive.

There was, among the Gentiles, no inclination or tendency towards God. This does not mean that they were physically depraved, or that their disposition was literally like the wild olive; but this is used, for the sake of illustration, to show that their moral character and habits were unlike those of the friends of God.

Regarding nature, not as it was made at first, but as it was corrupted in Adam, and so passed on from him to his posterity into the people of the Jews, whom God had sanctified only by His grace: and Paul here speaks of the whole nation, not of any one part.

“how much more shall these”– If God can do this much as He has already done, then “how much more” can He do?  It is reasonable to conclude that He can, and will, take back His natural branches and graft them back in again.

         HOW MUCH MORE (Grk.–posōi mallon)–Then “how much more?”  God can graft the natural Israel back upon the spiritual Israel, if they become willing.

         The meaning of this whole verse may be thus expressed: “If God had mercy on the Gentiles, who were outcasts from His favor, shall he not much rather on those who were so long his people, to whom had been given the promises, and the covenants, and the law, whose ancestors had been so many of them his friends and among whom the Messiah was born?” 
          In some respects there are facilities among the Jews for their conversion, which had not existed among the Gentiles. They worship one God; they admit the authority of revelation; they have the Scriptures of the O.T. they expect a Messiah; and they have a habit of professed reverence for the will of God.

“For I would not, brethren, that ye should be ignorant of this mystery, lest you should be wise in your own conceits; that blindness in part is happened to Israel, until the fullness of the Gentiles is come.”

            “ignorant of this mystery”
           “To be ignorant of this mystery.”–Any secret thing, known to but a few, is called a “mystery.”

          MYSTERY:  (Grk.–mustêrion)–The word “mystery” means that which is concealed, hidden, or unknown.  And in the N.T.it refers to the truths or doctrines which God had reserved to Himself, or had not before communicated.  The doctrine, that the division between the Jews and the time of the apostles,  and was then revealed fully for the first time, (16:25; Col. 1:26-27; comp. I Cor. 15:51; Mark 4:11; Eph. 1:9; 3:3).

           “Mystery” does not mean, as often with us, that there was anything unintelligible or inscrutable in the nature of the doctrine itself, for it was commonly perfectly plain when it was made known.  The mystery that Paul is about to unfold is concerning the conversion of Israel.  He unfolds it lest the Gentile Christians may have incorrect views, or “be wise in their own conceits.”
          Not in the pagan sense of an esoteric doctrine for the unknown secrets (II Thess. 2:7), or like the
mystery religions of that time, but the revealed will of God now made known to all (I Cor. 2:1,7; 4:1) which includes Gentiles also (16:25; Col. 1:26; Eph. 3:3) and so far superior to man's wisdom (Col. 2:2; 4:13; Eph. 3:9; 5:32; 6:19; Matt. 13:11; Mark 4:11). Paul has covered every point of difficulty concerning the failure of the Jews to accept Jesus as the Messiah and has shown how God has overruled it for the blessing of the Gentiles with a ray of hope still held out for the Jews .

“In early ecclesiastical Latin, mustêrion was rendered by sacramentum, which in classical Latin means the military oath. The explanation of the word sacrament, which is so often founded on this etymology, is therefore mistaken, since the meaning of a sacrament belongs to mustêrion and not to sacramentum in the classical sense"–Vincent)

         “lest ye should be wise in your own conceits”
         Literally:  “So that you may not be wise within yourselves.” —Rather than leave them to vain speculations and self-gratification.

 Paul chose to cut short all inquiry by stating the truth about their present and future state. He states the truth in regard to this, lest they should Jews.   That is, that they should be elated with the belief that they had,    by their own skill and genius  figured out the cause.

           WISE IN YOURSELVES:  (Grk.–par’ heautois phronimoi)-Some MSS. read par' heautois, or “by yourselves”.  Here we see that Paul has a negative purpose to prevent self-conceit on the part of the Gentile believers;  to show them that they had no merit in themselves

From this, it and also from other expressions in this epistle, it seems that the converted Gentiles had not behaved toward the Jews with that decorum and propriety which the relation they possessed required of them. In this chapter Paul warns them against giving way to such a disposition.

“that blindness in part is happened to Israel”
Literally:  “That hardness {in} part has happened to Israel.” This blindness, or hardening, had been due to Israel's sins, especially to their unbelief. The second fact is that this would continue.

            BLINDNESS:  (Grk.–pōrōsis)–Or hardness (v. 7). From (Grk.–pôroô) (v. 7).   This Greek word occurs in Hippocrates as a medical term. Used only here in the N.T. and Mark 3:5; Eph. 4:18. It means denseness or dullness of intellectual discernment; literally: mental dullness.

                        IN PART: (Grk.–merous)–Not totally, or entirely. They all are not blind.

         This is a qualifying expression; but it does not denote what part, or portion, or for what time it is to continue. It means that the blindness in respect to the whole nation was only partial.  Some were then enlightened, and had become Christians; and many more would be. Several thousands of them had already been converted to the Christian faith; though the body of the nation, and especially its rulers, both civil and spiritual, continued opposed to Christ and His doctrine.                                 

“until the fullness of the Gentiles is come”
Literally: “Until the fullness of the nations comes in.”–This blindness will continue till the Church of the Gentiles is fully completed; till the Gospel be preached through all the nations of the earth, and multitudes of Gentiles everywhere embrace the faith. Or the greater part of the Gentiles world been converted.

        FULLNESS: (Grk.–plêrōma)–This word, in relation to the Jews, is also used in v. 12. It means, until the abundance or the great multitude of the Gentiles shall be converted.

         The word is not used anywhere else in respect to the Gentiles; and it is really difficult to definitely or to fix its literal meaning. It doubtless refers to the future spread of the Gospel among the Gentile nations; to that time when it may be said that the great mass, the abundance of the nations, shall be converted to God.
         At present they are, as they were in the times of the apostle, idolaters, so that the mass of mankind are far from God. But the Scriptures have spoken of a time when the Gospel shall spread and prevail among the nations of the earth. To this Paul is referring; however, he does not say that the Jews may not be converted until all the Gentiles become Christians; for he expressly supposes (verses 12-15) that the conversion of the Jews will have an important influence in extending the Gospel among the Gentiles.
         Probably the meaning is that this blindness is to continue until great numbers of the Gentiles shall be converted; until the Gospel shall be extensively spread; and then the conversion of the Jews will be a part of the rapid spread of the Gospel, and will be among the most efficient and important aids in completing the work. If this is the case, then Christians may labor still for their conversion. They may seek that in connection with the effort to convert the Gentiles; and they may toil with the expectation that the conversion of the Jews and Gentiles will not be separate, independent, and distinct events; but will be intermingled, and will perhaps be simultaneous.  

 VERSE 26:
“And so all Israel shall be saved:  as it is written, ‘There shall come out of Sion the Deliverer; and shall turn away ungodliness from Jacob.’”
When this ingathering of the Gentiles is complete, then Israel will come round again, and the prophecies of their conversion will be fulfilled.

“And so all Israel shall be saved”
“And so all Israel will be saved.”–Shall be brought into the way of salvation, by acknowledging the Messiah.  No man can receive conceive that a time will ever come in which every Jew then living, shall be taken to the Kingdom of Glory.

After the fullness of the Gentiles has come in, the Jews, as a people, shall be saved. That is, of the Jews then living, the great part shall be converted. The nation shall turn to the Lord.

        AND SO:  (Grk.–kai houtos)–That is, in this manner; or when the great abundance of   the Gentiles shall be converted, then all Israel shall be saved, by the complement of the Gentiles stirring up the complement of the Jews (v. 11). 

        ALL ISRAEL:  (Grk.–pas Israel)–All the Jews.  It was a maxim among the Jews, that “every Israelite should have part in the future age.”  The immediate context argues for the Jewish people “as a whole.”

Paul applies that maxim to his own purpose; and declares the sense in which it would be true. He does not mean to say that every Jew of every age would be saved, for he had proved that a large portion of them would be, in his time, rejected and lost. But the time would come when, as a people, they would be recovered; when the nation would turn to God; and when it could be said of them, that, as a nation, they were restored to the Divine favor.

        SHALL BE SAVED:  (Grk.–sothesetai)–Shall be recovered from their rejection; will be restored to the favor of God; would become followers of the Messiah and thus be saved as all other Christians are.

The term saved, as applied to the Israelites in different parts of the Scripture, signifies no more than their being gathered out of the nations of the world, separated to God, and possessed of the high privilege of being His peculiar people.  And we know that this is the meaning of the term, by finding it applied to the body of the Israelites when this alone was the sum of their state.

“as it is written”
Literally: “Even as it has been written.”–In Isaiah 59:20. Paul does not literally quote this   passage of Scripture: but he does cite the sense of Isa 59:20,21 and Isa 27:9.  He supports what he presents by a quotation from Scripture, which, in the main, is taken from Isa 59:20:

“There shall come out of Sion the Deliverer”
Literally:  “The Deliverer will come out of Zion.”–The Hebrew is, “There shall come to Zion a Redeemer, and for those who turn from ungodliness in Jacob.”  There can be no doubt that Isaiah here referring to to the times of the

          Zion was one of the hills of Jerusalem, and on this hill was built the City of David.  Thus it came to generally denote the people of God. And when it is said that the Redeemer should come out of Zion, it means that He should arise among that people; be descended from themselves; or should not be a foreigner. The Septuagint (LXX), renders it as, “the Redeemer shall come on a Mount of Zion.”
         The Deliverer  (Redeemer)  shall come out of Zion, and turn away ungodliness from Jacob (National Israel). The fulfillment of this prophecy is still in the future..  In what manner Christ is to come out of Zion, and in what way or by what means He is to turn away transgression from Jacob, we cannot know; and to attempt to conjecture, when the time, occasion, means, etc.., are all in mystery, would be more than reprehensible.  There are three aspects of the Second Coming of Christ:
1.         For the “rapture” (calling out) of the Church.
2.         For the Judgment of the Nations (Matthew 25:31ff).
3.        For the deliverance of Israel.

          The prophet announces that “the Redeemer (or 'Deliverer') shall come to (or ‘for’) Zion” (Isa 59:20).  But as all the glorious manifestations of Israel's God were regarded as issuing out of Zion, as the seat of His manifested glory (Ps 20:2; 110:2; Isa 31:9), the turn which Paul here gives to the words merely adds to them that familiar idea.
          And whereas the prophet announces that He “shall come to (or, ‘for’) them that turn from transgression in Jacob,” while Paul makes him say that He shall come “to turn away ungodliness from Jacob,” this is taken from the Septuagint (LXX) version, and seems to indicate a different reading of the original text. The sense, however, is substantially the same in both.

 REDEEMER:  (Grk.–rhuomenos)–The Rescuer; same word as I Thess. 1:10“who rescueth us from the wrath to come.”  

The Hebrew word for “redeemer” is goel, or the avenger, that is, the nearest relative of a murdered person, on whom devolved the duty of avenger, wa s called goel haddam-the avenger of blood.The goel also was the nearest kinsman of a childless widow, and was required to marry her (Deut. 25:5-10).   It is the word used by Job in the celebrated passage (Job 19:25).  Also see Ruth 3:12-13; 4:1-10.

“For I know {that} my redeemer liveth, and {that} He shall stand at the latter {day} upon the earth” (Job 19:25).

“shall turn away ungodliness from Jacob”
Literally: “He will turn away ungodliness from Jacob.”–Convert to righteousness the  descendants of Jacob, the Jews.  The Hebrew is, “to those forsaking ungodliness in Jacob.” The Septuagint (LXX) has rendered it in the same manner as Paul.          

Israel as a nation, and not as it is now, a remnant of believing individuals.  As it is written; (Isa. 59:20-21; Psa. 14:7; Jer. 31:31-34; Heb. 10:15-18).  However great the present blindness, or “hardness” of the Jews, however strong their opposition to Jesus of Nazareth, the time is coming when they will know that He is their long-promised Messiah, will embrace Him as their hope of glory, and will become eminent benefactors of the world. With reference to this they have been kept as a distinct people; and all exulting over them by the Gentiles is highly offensive to God.

“For this is My covenant unto then, when I shall take away their sins”

           “For this is My covenant”
           Literally: “And {again} this is My covenant with them.”–This expression is found  immediately following the other in Isa 59:21.

         This is what God has promised to them in covenant, and He will be as good as His Word His covenant will never be broken.  It will always remain sure and inviolable, so that there is not only a possibility, and a probability, but even a certainty, of the call and conversion of the Jews; which promise and covenant will have their accomplishment,      

         Paul connects with it a part of another promise taken from Jer. 31:33-34; or rather he edits that promise, and expresses its substance by adding, “when I shall take away their sins,”  It is clear that he intended to express the general sense of the promises, as they were well known to the Jews.  This was a subject which he did not need to argue or reason with them, that God had made a covenant with them, and intended to restore them if they were cast off, and should then repent and turn to him.

           “I shall take away their sins”
           Literally:  “when I take away their sins.”–God’s covenant unto them is to, “Take away their sins.”  


          “As for Me, this is My covenant with them, saith the LORD. My Spirit that is upon thee, and My words which I have put in thy mouth, shall not depart out of thy mouth, nor out of the mouth of thy seed, nor out of the mouth of thy seed's seed,” saith the LORD from henceforth and forever.
          Obviously these passages imply the restoration of Israel to the God’s favor. And the Redeemer shall come to Zion, to them that turn from transgression in Jacob, says the LORD.

“This, we believe, is rather a brief summary of Jer. 31:31-34 than the express words of any prediction, Those who believe that there are no predictions regarding the literal Israel in the O.T., that stretch beyond the end of the Jewish economy, are obliged to view these quotations by the apostle as mere adaptations of Old Testament language to express his own predictions.”–Alexander

It might be appropriate to here add some more O.T. passages that point to the restoration of the nation of Israel.
Isaiah 2:2-5; 19:24-25; 25:6, etc.;  30:18-19, 26; 60:1-22; 65:17-25; Jeremiah 31:10-12; 46:27-28; Ezekiel 20:34, 40, etc..; 28:25,26; 34:20, etc.; 36:8-16; 37:21-28; 39:25; Joel 3:1-2, 17, 20-21; Amos 9:9-15; Obadiah 1:17; 21; Zephaniah 3:19-20; Micah 4:3-7; 7:18-20