If you believe 1 Corinthians 15:1-4 is all there is to the Gospel, you my friend have a very unbiblical and limited understanding of it.
Galatians 2:11-14
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?
Did they walk not according to 1 Corinthians 15:1-4? Did they stop believing Jesus died for their sins etc? No. The truth of the Gospel talked about here is there is no separation between Jew and Gentile in salvation.
Mark 1:1 the BEGINNING of the Gospel of Jesus the Messiah, the son of God.
The Gospel includes the death burial and resurrection of Jesus yes. But it is important to mention the Gospel of the Kingdom, the kingdom is coming and we are in training for that kingdom, the teachings of Jesus are of utmost importance, not just His death and burial and resurrection.
Galatians 2:11-14
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?
Did they walk not according to 1 Corinthians 15:1-4? Did they stop believing Jesus died for their sins etc? No. The truth of the Gospel talked about here is there is no separation between Jew and Gentile in salvation.
Mark 1:1 the BEGINNING of the Gospel of Jesus the Messiah, the son of God.
The Gospel includes the death burial and resurrection of Jesus yes. But it is important to mention the Gospel of the Kingdom, the kingdom is coming and we are in training for that kingdom, the teachings of Jesus are of utmost importance, not just His death and burial and resurrection.
Eph 1:13 In whom ye also trusted, after that ye heard the word of truth, the gospel of your salvation: in whom also after that ye believed, ye were sealed with that holy Spirit of promise,
They heard the word of truth the gospel and believed, and were saved and sealed.
They walked not uprightly according to the truth of the gospel. That is exactly what it says.
Believers are to walk honestly so that others may see their light. Peter was a kingdom gospel saint.
He did not have the same gospel as Paul.
Gal 2:7 But contrariwise, when they saw that the gospel of the uncircumcision was committed unto me, as the gospel of the circumcision was unto Peter;