Galatians 2:1 Then fourteen years after I went up again to Jerusalem with Barnabas, and took Titus with me also.
[2] And I went up by revelation, and communicated unto them that gospel which I preach among the Gentiles, but privately to them which were of reputation, lest by any means I should run, or had run, in vain.

The events are recorded in Acts chapter 15 where it was determined by the Apostles, elders and the Holy Ghost the Gentile believers were not under the bondage of Moses. (Acts 15:6-11,20-21,28)
What amazes me is there are still today those who would attempt to put Christians under the bondage of the law even after this dispute was settled in the infancy of the church.

[3] But neither Titus, who was with me, being a Greek, was compelled to be circumcised:
[4] And that because of false brethren unawares brought in, who came in privily to spy out our liberty which we have in Christ Jesus, that they might bring us into bondage:

The outward fleshly acts in no wise saves a man. It is but not a combination of grace and works. (Ephesians 2:8-9)
Please note the reference from Paul to “my gospel” Romans 2:16/ Romans 16:25/ 11 Timothy 2:8 (1 Timothy 1:11/Philippians 1:1-7/ 1 Corinthians 9:17)

If the gospel message Paul was preaching was the same as the one Peter was preaching then there would be no need for explanation. The gospel of the grace of God was kept a mystery until revealed to the Apostle Paul. With the completion of the New Testament canon the gospel was revealed, codified and disseminated.

In Acts 18 we find Apollos preaching the kingdom gospel of John. Peter preaching baptism as a requirement of salvation to Jews only (Acts 2:38). Even after the conversion of Cornelius we find as late as Acts 11:19 those scattered only preached to the Jews. There existed no conflict until the conversion of Gentiles became evident as God’s plan because the Jews already were circumcised and followed after the law.

Acts 18:[24] And a certain Jew named Apollos, born at Alexandria, an eloquent man, and mighty in the scriptures, came to Ephesus.
[25] This man was instructed in the way of the Lord; and being fervent in the spirit, he spake and taught diligently the things of the Lord, knowing only the baptism of John.
[26] And he began to speak boldly in the synagogue: whom when Aquila and Priscilla had heard, they took him unto them, and expounded unto him the way of God more perfectly.
[27] And when he was disposed to pass into Achaia, the brethren wrote, exhorting the disciples to receive him: who, when he was come, helped them much which had believed through grace:
[28] For he mightily convinced the Jews, and that publickly, shewing by the scriptures that Jesus was Christ.

Here we have a preacher with limited knowledge of Christianity preaching (vs. 25). Two of Paul’s co-workers hear him and realize his knowledge is limited and explain to him more fully the true gospel. It seems evident there was a difference in what God had given to Paul and what was known until the time it was revealed. After being made more fully aware and through his knowledge of the Old Testament and eloquent ability to speak he was able to help the brethren who had already trusted in Christ through the message of grace.
The modern Bible student must keep in mind we have the complete revealed will of God in our hands. At the time then current the Book was being revealed and written. God deals with humanity according to His revealed will and their reception or rejection of it.

[5] To whom we gave place by subjection, no, not for an hour; that the truth of the gospel might continue with you.
[6] But of these who seemed to be somewhat, (whatsoever they were, it maketh no matter to me: God accepteth no man’s person:) for they who seemed to be somewhat in conference added nothing to me:
[7] But contrariwise, when they saw that the gospel of the uncircumcision was committed unto me, as the gospel of the circumcision was unto Peter;
[8] (For he that wrought effectually in Peter to the apostleship of the circumcision, the same was mighty in me toward the Gentiles:)
[9] And when James, Cephas, and John, who seemed to be pillars, perceived the grace that was given unto me, they gave to me and Barnabas the right hands of fellowship; that we should go unto the heathen, and they unto the circumcision.
[10] Only they would that we should remember the poor; the same which I also was forward to do.

There are two sides to this passage. On one hand there are those who believe their gospels were the same just a clear delineation between to whom they were preaching and there are those who believe there were two gospels being preached with two different audiences.

Let me reiterate:
1) If the two gospels were the same there would be no need for Paul to go to Jerusalem to explain the gospel he was preaching.
2) Apollos would have been preaching the same thing at the beginning of his ministry.

I feel there were two different gospels at the time. Until the full revelation given to Paul was revealed to all I believe Peter, James and John preached the same message as found in early Acts. One of repentance from “murdering” Jesus and baptismal regeneration as a requirement.
A reading of their writings shows no knowledge of the Rapture and just a simple glance at the book of James clearly indicates he was writing to the Jews (James 1:1). Throughout the book it is evident it is written without a perspective of the gospel of grace given to the Apostle Paul. The words blood, cross, gospel, are not mentioned and the only mention of forgiveness is based on a conditional prayer of faith involving the sick. James goes so far as to write works are a requirement for salvation.
I believe in properly dividing the Word of God by intended audience and time. I believe as it says in Hebrews (Hebrews 2:5) there are writings for the next age and direct application of many verses awaits a time to come.
After the completion of the New Testament it became transparent we are to preach the gospel as given to the Apostle Paul. For the time now present we must stick to the gospel as revealed to the Apostle Paul.

[11] But when Peter was come to Antioch, I withstood him to the face, because he was to be blamed.
[12] For before that certain came from James, he did eat with the Gentiles: but when they were come, he withdrew and separated himself, fearing them which were of the circumcision.
[13] And the other Jews dissembled likewise with him; insomuch that Barnabas also was carried away with their dissimulation.
[14] But when I saw that they walked not uprightly according to the truth of the gospel, I said unto Peter before them all, If thou, being a Jew, livest after the manner of Gentiles, and not as do the Jews, why compellest thou the Gentiles to live as do the Jews?

Peter was being two faced. Knowing the liberty we have in Christ yet in order to not rock the boat pretended to follow the law when in the company of the Jews. According to verse 14 Peter was also teaching compliance to the law to the Gentiles. Wherein is proof Peter was preaching a different gospel than Paul.

[15] We who are Jews by nature, and not sinners of the Gentiles,
[16] Knowing that a man is not justified by the works of the law, but by the faith of Jesus Christ, even we have believed in Jesus Christ, that we might be justified by the faith of Christ, and not by the works of the law: for by the works of the law shall no flesh be justified.
[17] But if, while we seek to be justified by Christ, we ourselves also are found sinners, is therefore Christ the minister of sin? God forbid.
[18] For if I build again the things which I destroyed, I make myself a transgressor.
[19] For I through the law am dead to the law, that I might live unto God.

Not only are the Gentiles not under the law but the Jews also were no longer under the bondage but were to be saved through grace by faith. Peter makes the same statement in Acts. (Acts 15:11)

Jews by “nature” meaning by natural birth. (Romans 2:27/Romans 11:21&24) The “we” of this verse are the Jewish believers like Paul and the other Apostles. The Jews like the Gentiles must also come through the grace of God by faith in Jesus Christ and not by the works of the law which had originally been taught by the other Apostles. (Acts 15:8-11)
If Paul attempts to live under the law again he is being unfaithful to the truth and liberty of the gospel . He is basically putting his sins back on himself and off of Christ who has paid the price. The sin under the law being paid in full by Jesus and now we who are in Christ through Christ have been paid for and are now dead to the law.

Philippians 3:1 Finally, my brethren, rejoice in the Lord. To write the same things to you, to me indeed is not grievous, but for you it is safe.
[2] Beware of dogs, beware of evil workers, beware of the concision.
[3] For we are the circumcision, which worship God in the spirit, and rejoice in Christ Jesus, and have no confidence in the flesh.
[4] Though I might also have confidence in the flesh. If any other man thinketh that he hath whereof he might trust in the flesh, I more:
[5] Circumcised the eighth day, of the stock of Israel, of the tribe of Benjamin, an Hebrew of the Hebrews; as touching the law, a Pharisee;
[6] Concerning zeal, persecuting the church; touching the righteousness which is in the law, blameless.
[7] But what things were gain to me, those I counted loss for Christ.
[8] Yea doubtless, and I count all things but loss for the excellency of the knowledge of Christ Jesus my Lord: for whom I have suffered the loss of all things, and do count them but dung, that I may win Christ,
[9] And be found in him, not having mine own righteousness, which is of the law, but that which is through the faith of Christ, the righteousness which is of God by faith:

The things Paul had destroyed were the works of righteousness he had under the law. Knowing they in no way brought salvation.

Romans7:[1] Know ye not, brethren, (for I speak to them that know the law,) how that the law hath dominion over a man as long as he liveth?
[2] For the woman which hath an husband is bound by the law to her husband so long as he liveth; but if the husband be dead, she is loosed from the law of her husband.
[3] So then if, while her husband liveth, she be married to another man, she shall be called an adulteress: but if her husband be dead, she is free from that law; so that she is no adulteress, though she be married to another man.
[4] Wherefore, my brethren, ye also are become dead to the law by the body of Christ; that ye should be married to another, even to him who is raised from the dead, that we should bring forth fruit unto God.
[5] For when we were in the flesh, the motions of sins, which were by the law, did work in our members to bring forth fruit unto death.
[6] But now we are delivered from the law, that being dead wherein we were held; that we should serve in newness of spirit, and not in the oldness of the letter.

[20] I am crucified with Christ: nevertheless I live; yet not I, but Christ liveth in me: and the life which I now live in the flesh I live by the faith of the Son of God, who loved me, and gave himself for me.
[21] I do not frustrate the grace of God: for if righteousness come by the law, then Christ is dead in vain.

We who are Christians have now put on Christ and are living testaments to the grace of God. We should now live a life that conforms to the image of Christ. Jesus died and our selves should be dead with Him.