First, to cut it out from among the other gospels found in the Bible, such as the one in the four gospels and Hebrews-Revelation.
Secondly, even though our gospel is found in all 13 letters of Paul, we should consider which ones were written before the mystery of the gospel was revealed.
Then why the exact same sense in 1 Corinthians 12 thru 14 as Romans 12 thru 15 and Ephesians 2 thru 4?
A simple example.
Romans 12:
1. I beseech you therefore, brethren,
by the mercies of God, that ye present your bodies a living sacrifice, holy, acceptable unto God, which is your reasonable service.
2. And be not conformed to this world: but be ye transformed by the renewing of your mind, that ye may prove what is that good, and acceptable, and perfect, will of God.
3. For I say, through the grace given unto me, to every man that is among you, not to think of himself more highly than he ought to think; but to think soberly, according as God hath dealt to every man the measure of faith.
4. For as we have many members in one body, and all members have not the same office:
5. So we, being many, are one body in Christ, and every one members one of another.
Romans 15:
7. Wherefore receive ye one another,
as Christ also received us to the glory of God.
13. Now the God of hope fill you with all joy and peace in believing, that ye may abound in hope, through the power of the Holy Ghost.
14. And I myself also am persuaded of you, my brethren, that ye also are full of goodness, filled with all knowledge, able also to admonish one another.
15. Nevertheless, brethren, I have written the more boldly unto you in some sort, as putting you in mind, because of the grace that is given to me of God,
16. That I should be the minister of Jesus Christ to the Gentiles, ministering the gospel of God, that the offering up of the Gentiles might be acceptable, being sanctified by the Holy Ghost.
1 Corinthians 12:
1. Now concerning spiritual gifts, brethren, I would not have you ignorant.
2.
Ye know that ye were Gentiles, carried away unto these dumb idols, even as ye were led.
3. Wherefore I give you to understand, that no man speaking by the Spirit of God calleth Jesus accursed: and that no man can say that Jesus is the Lord, but by the Holy Ghost.
4. Now there are diversities of gifts, but the same Spirit.
Ephesians 2:
11.
Wherefore remember, that ye being in time past Gentiles in the flesh, who are called Uncircumcision by that which is called the Circumcision in the flesh made by hands;
12.
That at that time ye were without Christ, being aliens from the commonwealth of Israel, and strangers from the covenants of promise, having no hope, and without God in the world:
13.
But now in Christ Jesus ye who sometimes were far off are made nigh by the blood of Christ.
18. For through him we both have access by one Spirit unto the Father.
Ephesians 3:
1. For this cause I Paul, the prisoner of Jesus Christ for you Gentiles,
2. If ye have heard of the dispensation of the grace of God which is given me to you-ward:
3. How that by revelation he made known unto me the mystery; (as I wrote afore in few words,
4. Whereby, when ye read, ye may understand my knowledge in the mystery of Christ)
5. 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;
6.
That the Gentiles should be fellowheirs, and of the same body, and partakers of his promise in Christ by the gospel:
7. Whereof I was made a minister, according to the gift of the grace of God given unto me by the effectual working of his power.
Ephesians 4:
1. I therefore, the prisoner of the Lord, beseech you that ye walk worthy of the vocation wherewith ye are called,
2. With all lowliness and meekness, with longsuffering, forbearing one another in love;
3. Endeavouring to keep the unity of the Spirit in the bond of peace.
4. There is one body, and one Spirit, even as ye are called in one hope of your calling;
5. One Lord, one faith, one baptism,
6. One God and Father of all, who is above all, and through all, and in you all.
7.
But unto every one of us is given grace according to the measure of the gift of Christ.
In short, this here:
1 Corinthians 12: 2.
Ye know that ye were Gentiles, carried away unto these dumb idols, even as ye were led.
Is this here:
Ephesians 2: 11.
Wherefore remember, that ye being in time past Gentiles in the flesh, who are called Uncircumcision by that which is called the Circumcision in the flesh made by hands;
Both passages speak of where God had left the Gentiles off in Genesis 11,
until the Mystery [singular, not plural].
In both passages, Paul is talking about prior, overall, Gentile status, in general, before the revelation of the Mystery of the one New Man.
2 Kings 17:
9. And the children of Israel did secretly those things that were not right against the LORD their God, and they built them high places in all their cities, from the tower of the watchmen to the fenced city.
10. And they set them up images and groves in every high hill, and under every green tree:
11. And there they burnt incense in all the high places,
as did the heathen whom the LORD carried away before them; and wrought wicked things to provoke the LORD to anger:
12. For they served idols, whereof the LORD had said unto them, Ye shall not do this thing.
Psalm 115:
4. Their idols are silver and gold, the work of men's hands.
5. They have mouths, but they speak not: eyes have they, but they see not:
6. They have ears, but they hear not: noses have they, but they smell not:
7. They have hands, but they handle not: feet have they, but they walk not: neither speak they through their throat.
8. They that make them are like unto them; so is every one that trusteth in them.
9. O Israel, trust thou in the LORD: he is their help and their shield.