Christians can show you a summary of the Christian Gospel (quite different to the gospel of Jesus) in Paul’s letter 1 Corinthians 15: 3-4. Paul is so clear what it means and how the Jewish Scriptures clearly speak of the death of Christ for our sins, how Jesus was buried and raised from the grave on the 3rd day all “in accordance with the Jewish Scriptures” – that few stop to wonder which passages in the OT say these things about the promised Messiah. Many Christians will be bewildered to find that there are no such passages anywhere in the Bible that prophesy any of these things about the Christ. Respected evangelical Bible study guides like the NIV Study Bible are not certain which passages Paul had in mind, commenting that Paul “probably” had in mind Isaiah 53, “but he may [may?!] have have been thinking of the OT sacrificial system” (p. 1796).
When Paul claims that the Christ would be ‘raised on the 3rd day all in accordance with the Jewish Scriptures‘ the NIV Study Bible weakly suggests that he might have had Psalm 16: 8-11 “in mind” but it says absolutely nothing about the messiah, his death for sins, nor his rising from the dead on the 3rd day!
Nowhere in the ‘OT sacrificial system’ is there any provision for human sacrifice to atone for sins. In fact God repeatedly condemns human sacrifices as ‘abominations’. So the NIV Study Bible cannot be correct at that point. This fact also rules out the popular Christian spin on Isaiah 53 as God explicitly rejects human sacrifices. Besides, the passage does not mention a Messiah, nor his rising from the dead on the 3rd day.
So all in all Paul’s own gospel would appear to based on a fabrication. And why should anyone believe in that?