1Co 15:3 For I delivered unto you first of all that which I also received, how that Christ died for our sins according to the scriptures;
1Co 15:4 And that he was buried, and that he rose again the third day according to the scriptures:
Paul was chosen by God to preach the gospel he had received from Christ.
Gal 1:11 But I certify you, brethren, that the gospel which was preached of me is not after man.
Gal 1:12 For I neither received it of man, neither was I taught it, but by the revelation of Jesus Christ.
Which gospel are you trusting for salvation?
Gal 1:6 I marvel that ye are so soon removed from him that called you into the grace of Christ unto another gospel:
Gal 1:7 Which is not another; but there be some that trouble you, and would pervert the gospel of Christ.
Gal 1:8 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.
Gal 1:9 As we said before, so say I now again, If any man preach any other gospel unto you than that ye have received, let him be accursed.
Why Paul's gospel only?
This gospel Paul had received from Christ was not known before it was revealed to him.
Eph_3:9 And to make all men see what is the fellowship of the mystery, which from the beginning of the world hath been hid in God, who created all things by Jesus Christ:
Eph_6:19 And for me, that utterance may be given unto me, that I may open my mouth boldly, to make known the mystery of the gospel,
Rom_16:25 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,
There is no other gospel for you to be saved by today.