It's not the same gospel.
Peter preached the same Gospel to the jews and gentiles. Acts 15:6-9
And the apostles and elders came together for to consider of this matter. 7 And when there had been much disputing, Peter rose up, and said unto them, Men and brethren, ye know how that a good while ago God made choice among us, that the Gentiles by my mouth should hear the word of the gospel, and believe. 8 And God, which knoweth the hearts, bare them witness, giving them the Holy Ghost, even as he did unto us;
and put no difference between us and them, purifying their hearts by faith
Acts 15 comes AFTER Acts 9.
Acts 15 is around 20 years after Paul's conversion.
Galatians 1:18 is where Paul tells Peter (and James, the Lord's brother) about his testimony. Fourteen years later, in Galatians 2:1, Paul again goes, in private, to the twelve, to show them his gospel.
Beloved57, could you explain for me please why Paul, if what you say is true and his gospel is the same, went to the twelve in private to convey to them what he was teaching his converts?
Why hide it from the church?
My answer is that it's because their messages are so different, that had Paul gone and preached his gospel to the Jews 14 years after Galatians 1:18, he would have been thrown out of the church as a heretic, since his gospel preached faith alone, while Peter's congregation was taught to keep the law under the New Covenant.
So what is your answer to this scripture:
Then after fourteen years I went up again to Jerusalem with Barnabas, and also took Titus with me.And I went up by revelation, and communicated to them that gospel which I preach among the Gentiles, but privately to those who were of reputation, lest by any means I might run, or had run, in vain.Yet not even Titus who was with me, being a Greek, was compelled to be circumcised.And this occurred because of false brethren secretly brought in (who came in by stealth to spy out our liberty which we have in Christ Jesus, that they might bring us into bondage),to whom we did not yield submission even for an hour, that the truth of the gospel might continue with you.But from those who seemed to be something—whatever they were, it makes no difference to me; God shows personal favoritism to no man—for those who seemed to be something added nothing to me.But on the contrary, when they saw that the gospel for the uncircumcised had been committed to me, as the gospel for the circumcised was to Peter(for He who worked effectively in Peter for the apostleship to the circumcised also worked effectively in me toward the Gentiles),and when James, Cephas, and John, who seemed to be pillars, perceived the grace that had been given to me, they gave me and Barnabas the right hand of fellowship, that we should go to the Gentiles and they to the circumcised.They desired only that we should remember the poor, the very thing which I also was eager to do.Now when Peter had come to Antioch, I withstood him to his face, because he was to be blamed;for before certain men came from James, he would eat with the Gentiles; but when they came, he withdrew and separated himself, fearing those who were of the circumcision.And the rest of the Jews also played the hypocrite with him, so that even Barnabas was carried away with their hypocrisy.But when I saw that they were not straightforward about the truth of the gospel, I said to Peter before them all, “If you, being a Jew, live in the manner of Gentiles and not as the Jews, why do you compel Gentiles to live as Jews?We who are Jews by nature, and not sinners of the Gentiles,knowing that a man is not justified by the works of the law but by faith in Jesus Christ, even we have believed in Christ Jesus, that we might be justified by faith in Christ and not by the works of the law; for by the works of the law no flesh shall be justified.“But if, while we seek to be justified by Christ, we ourselves also are found sinners, is Christ therefore a minister of sin? Certainly not!For if I build again those things which I destroyed, I make myself a transgressor.For I through the law died to the law that I might live to God.I have been crucified with Christ; it is no longer I who live, but Christ lives in me; and the life which I now live in the flesh I live by faith in the Son of God, who loved me and gave Himself for me.I do not set aside the grace of God; for if righteousness comes through the law, then Christ died in vain.” - Galatians 2:1-21
http://www.biblegateway.com/passage/?search=Galatians2:1-21&version=NKJV
