Ga 1:6-8 ¶ I marvel that ye are so soon removed from him that called you into the grace of Christ unto another gospel:
7 Which is not another; but there be some that trouble you, and would pervert the gospel of Christ.
8 But though we, or an angel from heaven, preach any other gospel unto you than that which we have preached unto you, let him be accursed.
There is a doctrine in certain areas of Christianity that claims there was and is a gospel for the Jewish ecclesia and a different gospel for the Gentile ecclesia. Based largely on the following verse.
Galatians 2:7 KJVS
 But contrariwise, when they saw that the gospel of the uncircumcision was committed unto me, as the gospel of the circumcision was unto Peter;
If you look in a Greek Interlinear you will find the word gospel does not appear a second time in Gal 2:7. http://www.scripture4all.org/OnlineInterlinear/NTpdf/gal2.pdf Paul makes it clear to the Galatians, that the gospel that certain Jews came to teach them, was not another gospel but a perverted gospel of grace. If one examines the scriptures you will see there has only been one gospel that was preached to both Jew and Gentile. Peter makes this clear at a council in Jerusalem, which addressed the matter of whether the Gentiles had to observe the law of Moses and be circumcised. Peter stated at that time, that the Jewish and Gentile members of the body of Christ, were to both have their hearts purified by faith and Peter further states the Jews will get salvation through the grace of the Lord Jesus in the same way as they.” They of course referring to the Gentiles and the yoke of bondage mentioned by Peter in verse 10, was the law of Moses of which man was not strong enough to bear.
Acts 15:7-11 And when there had been much discussion, Peter got up and said to them, My brothers, you have knowledge that some time back it was God’s pleasure that by my mouth the good news might be given to the Gentiles so that they might have faith.
8 And God, the searcher of hearts, was a witness to them, giving them the Holy Spirit even as he did to us;
9 Making no division between them and us, but making clean their hearts by faith.
10 Why then are you testing God, by putting on the neck of the disciples a yoke so hard that not even our fathers or we were strong enough for it?
11 But we have faith that we will get salvation through the grace of the Lord Jesus in the same way as they. Weymouth
Now the last verse bears repeating for a third time for those who think there was two different gospels.
Acts 15:11 But we have faith that we will get salvation through the grace of the Lord Jesus in the same way as they. Weymouth
Peter also endorsed Apostle Paul and his epistles.
2Pe 3:15-16 And account that the longsuffering of our Lord is salvation; even as our beloved brother Paul also according to the wisdom given unto him hath written unto you;
16 As also in all his epistles, speaking in them of these things; in which are some things hard to be understood, which they that are unlearned and unstable wrest, as they do also the other scriptures, unto their own destruction.
It took me some time to realize that the longsuffering of the Lord, 2Pe 3:15, also includes the members of his body, Phil 3:10 & 1Pe 4:12-13. Further evidence of there being only one gospel is in the fact that Jesus, by his death, abolished the law of commandments contained in ordinances and made the two, Gentile and Jew, one new man.
Eph 2:13-15 But now in Christ Jesus ye who sometimes were far off are made nigh by the blood of Christ.
14 ¶ For he is our peace, who hath made both one, and hath broken down the middle wall of partition between us;
15 Having abolished in his flesh the enmity, even the law of commandments contained in ordinances; for to make in himself of twain one new man, so making peace;
So how can there be two gospels? The whole gist of Gal 2:7 is that Paul was making it clear that God had appointed him to bring gospel of grace to the Gentiles, Acts 9:15. Paul was given the task of preaching the gospel of grace to the Gentiles and Peter was to bring the gospel of grace to the Jews, nothing more. I think several aspect that makes the whole two gospel misconception plausible is the mystery of God, and a improper understanding of grace. The mystery of God is Christ in you the hope of glory, Col 1:27. If you do a word study on the word mystery, you will find Paul was given the dispensation to disclose the mystery of God to the church at a specific point in time and that it filled up the word of God, Col 1;25-27.
Ephesians 3:3-6 KJVS
 How that by revelation he made known unto me the mystery; (as I wrote afore in few words,  Whereby, when ye read, ye may understand my knowledge in the mystery of Christ)  Which in other ages was not made known unto the sons of men, as it is now revealed unto his holy apostles and prophets by the Spirit;  That the Gentiles should be fellowheirs, and of the same body, and partakers of his promise in Christ by the gospel:
Notice the wording in verse 6, fellowheirs, and of the same body. When you understand the significance of the mystery of God, you begin to realize that the gospels and epistles written before Paul disclosed the mystery of God, lack the entire gospel message regarding the salvation process. I don’t want to go overly long on this, but if you do a word study on the words mystery and sanctified as pertaining to the body of Christ, these words only appear in that context, after the mystery of God has been disclosed by God to Paul. The first three gospels lack knowledge of the mystery. The gospel of John was written much later, around 90AD, and contain verses that imply knowledge of the mystery of God spoken by the Lord himself.
John 12:24 KJVS
 Verily, verily, I say unto you, Except a corn of wheat fall into the ground and die, it abideth alone: but if it die, it bringeth forth much fruit.
John 17:17,23 KJVS
 Sanctify them through thy truth: thy word is truth.  I in them, and thou in me, that they may be made perfect in one; and that the world may know that thou hast sent me, and hast loved them, as thou hast loved me.
Being sanctified and made perfect are contingent upon the mystery of God which is Christ in you.
Hebrews 10:5,10 KJVS
 Wherefore when he cometh into the world, he saith, Sacrifice and offering thou wouldest not, but a body hast thou prepared me:  By the which will we are sanctified through the offering of the body of Jesus Christ once for all .
So the mystery of God is first mentioned by Paul in Ro 16:25. It is then a simple matter to find a list of when the gospels and epistles were written. You might, as I did, print it up, cut to size and tape it to the inside front or rear covers of your bible. The gospels and epistles written before the mystery was disclosed, are not going have verses in them that deal with sanctification of the body of Christ. Because again, sanctification is contingent about Christ in you. I think Peter sums it up nicely in 2Pe 3:16. Which is that, unlearned and unstable men wrestle with the scriptures unto their own destruction. The law of the Spirit of life in Christ Jesus, Ro 8:2, is about the heart. God, by His grace and by His Spirit is teaching us how to love one another, 1Th 4:9. Only by the grace of God teaching us and the washing of regeneration and renewal of the Holy Ghost changing us, can the purification of our hearts be accomplish, Titus 2:11&12, 3:5-7. In short the gospel of grace. The law was incapable of doing this because the flesh is too weak to observe the law.
Ro 8″1-4 ¶ There is therefore now no condemnation to them which are in Christ Jesus, who walk not after the flesh, but after the Spirit.
2 For the law of the Spirit of life in Christ Jesus hath made me free from the law of sin and death.
3 For what the law could not do, in that it was weak through the flesh, God sending his own Son in the likeness of sinful flesh, and for sin, condemned sin in the flesh:
4 That the righteousness of the law might be fulfilled in us, who walk not after the flesh, but after the Spirit.
There is only one gospel and that is the gospel of grace which saves us, Jew and Gentile alike, through the redemption that is in Christ Jesus, Ro 3:23-24. This graciousness of God, wherein He teaches us, chastises us and disciplines us, in tandem with the washing of regeneration and renewal of the Holy Ghost frequently in our lives, is how we are being saved, Tit 2:11-12, He 12:5-11, Titus 3:5-7. Included in this process is sanctification, which is the death of the flesh, that can only take place by the seed of Christ falling into our flesh, crucifying the flesh. The end result is being found in Christ at his coming and claiming our inheritance which God promised to Abraham, and to his seed. And that seed of course is Jesus Christ.
Galatians 3:16,29 KJVS
 Now to Abraham and his seed were the promises made. He saith not, And to seeds, as of many; but as of one, And to thy seed, which is Christ.  And if ye be Christ’s, then are ye Abraham’s seed, and heirs according to the promise.
That is the good news of the gospel of the Kingdom of God. But remember, just as there are vessels of mercy who were ordained for God’s purpose, so to, there are others ordained for a different purpose.
Jude 1:4 For there are certain men crept in unawares, who were before of old ordained to this condemnation, ungodly men, turning the grace of our God into lasciviousness, and denying the only Lord God, and our Lord Jesus Christ.