Paul longed to see them that he may impart to them some spiritual gift to the end they may be established
Romans 1:9-12 KJV For God is my witness, whom I serve with my spirit in the gospel of his Son, that without ceasing I make mention of you always in my prayers; 10 Making request, if by any means now at length I might have a prosperous journey by the will of God to come unto you. 11 For I long to see you, that I may impart unto you some spiritual gift, to the end ye may be established; :12 That is, that I may be comforted together with you by the mutual faith both of you and me.
So these Romans had a faith that was spoken of throughout the whole world, but but it was not the mutual faith of both Paul and them. Paul longed to see them that he may impart unto them some spiritual gift to the end they may be established that he may be comforted together with them by the mutual faith both of them and him.
I believe the Romans' faith was this, the gospel of God, concerning His Son Jesus Christ our Lord (the WHO of Jesus Christ) and declared to be the Son of God with power, according to the spirit of holiness, by the resurrection from the dead:
Romans 1:1-4 KJV Paul, a servant of Jesus Christ, called to be an apostle, separated unto the gospel of God, 2 (Which he had promised afore by his prophets in the holy scriptures,) 3 Concerning his Son Jesus Christ our Lord, which was made of the seed of David according to the flesh; :4 And declared to be the Son of God with power, according to the spirit of holiness, by the resurrection from the dead:
So what was the spiritual gift that Paul wanted to impart unto them that they may be established? It is Paul's "my gospel, and the preaching of Jesus Christ, according to the revelation of the mystery, which was kept secret since the world began, but now is made manifest,..."
Romans 16:25-27 KJV Now to him that is of power to stablish you according to my gospel, and the preaching of Jesus Christ, according to the revelation of the mystery, which was kept secret since the world began, 26 But now is made manifest, and by the scriptures of the prophets, according to the commandment of the everlasting God, made known to all nations for the obedience of faith: 27 To God only wise, be glory through Jesus Christ for ever. Amen.
These Romans had never heard the gospel of Christ. (1 Corinthians 15:1-4 KJV)
Romans 1:15-17 KJV So, as much as in me is, I am ready to preach the gospel to you that are at Rome also. 16 For I am not ashamed of the gospel of Christ: for it is the power of God unto salvation to every one that believeth; to the Jew first, and also to the Greek. 17 For therein is the righteousness of God revealed from faith to faith: as it is written, The just shall live by faith.
With this much ground to cover, on to the grafting in:
Romans 11:19-22 Thou wilt say then, The branches were broken off, that I might be graffed in. 20 Well; because of unbelief they were broken off, and thou standest by faith. Be not highminded, but fear: 21 For if God spared not the natural branches, take heed lest he also spare not thee. 22 Behold therefore the goodness and severity of God: on them which fell, severity; but toward thee, goodness, if thou continue in his goodness: otherwise thou also shalt be cut off.
This CANNOT be speaking of anyone in the Body of Christ for you CANNOT be CUT OFF! When you believe on the Lord Jesus Christ, trusting Him alone for your salvation; that He died for YOUR sins, was buried and rose again on the third day you are SEALED with that Holy Spirit of promise (the earnest of our inheritance) unto the day of redemption!
1 Corinthians 15:1-4 KJV Moreover, brethren, I declare unto you the gospel which I preached unto you, which also ye have received, and wherein ye stand; 2 By which also ye are saved, if ye keep in memory what I preached unto you, unless ye have believed in vain. 3 For I delivered unto you first of all that which I also received, how that Christ died for our sins according to the scriptures; 4 And that he was buried, and that he rose again the third day according to the scriptures:
Ephesians 1:13-14 KJV In whom ye also trusted, after that ye heard the word of truth, the gospel of your salvation: in whom also after that ye believed, ye were sealed with that holy Spirit of promise, 14 Which is the earnest of our inheritance until the redemption of the purchased possession, unto the praise of his glory.
Ephesians 4:30 KJV And grieve not the holy Spirit of God, whereby ye are sealed unto the day of redemption.
Notice there’s someone that Paul is focused on when he uses “thou” (which is singular in a King James Bible) and if you look back in Romans 2 you can see that this is someone that is “called a Jew”, rested in the law and made his boast of God:
Romans 2:17 KJV Behold, thou art called a Jew, and restest in the law, and makest thy boast of God,
Before anyone might jump to the conclusion that Paul is actually talking to a Jew, please remember that Paul is speaking to Gentiles.
Romans 1:13 KJV Now I would not have you ignorant, brethren, that oftentimes I purposed to come unto you, (but was let hitherto,) that I might have some fruit among you also, even as among other Gentiles.
This person in Romans 2 is someone who was bragging on his standing in the olive tree, but the natural branches had been broken off, for Israel had fallen and unless he continued in the goodness of God, he was in danger of being broken off too.
Believing the gospel that Paul preached (1 Corinthians 15:1-4 KJV) was the only way to “continue in His goodness” and upon believing be baptized by the Holy Spirit into the one Body!
1 Corinthians 12:13 KJV For by one Spirit are we all baptized into one body, whether we be Jews or Gentiles, whether we be bond or free; and have been all made to drink into one Spirit.