What is Paul saying about the gospel in 1 Corinthians 15? It is a passage about the resurrection of the body. The Greeks rejected bodily resurrection and the Corinthians sought some means to consolidate rejection of bodily resurrection with the gospel. Paul says, "No, can't be done. If you reject bodily resurrection, then you reject the resurrection of Jesus Christ, which is part of the gospel."
The Corinthians then really did find themselves in a situation that evangelicals now find themselves. The world doesn't like aspects of the gospel and evangelicals today seek to adapt the gospel to the world's tastes or philosophies, much like the Corinthians attempted. You were a Corinthian embarrassment believing in bodily resurrection, so Corinthians tried to reinvent a gospel without the offensive element.
Paul says that when I made known the gospel to you, I didn't leave out bodily resurrection -- I delivered not just death and burial, but also resurrection. You can't leave out the offensive element and still have the gospel.
There is an irony to how 1 Corinthians 15 is used today related to the gospel. Paul wrote it to stop minimization, and now his writing is used to promote it. How many groups can agree on death, burial, and resurrection? That formula excludes almost no Christian group from preaching a true gospel. Almost everyone can agree on that. You don't even have to believe the Trinity for inclusion in the death, burial, and resurrection coalition.
Before twitter ever began, 1 Corinthians 15:3-4 already existed as a ready made gospel tweet for gospel minimalists. Is Paul's point to reduce the gospel to a few words almost everyone could accept? He was excluding bodily resurrection rejection, which in Corinth was a big group. He was shrinking the coalition with bodily resurrection truth.
If you read 1 Corinthians in an honest and thinking fashion, you don't stop at verse four. The punctuation itself says "keep reading." Paul isn't minimizing. As you keep reading, because that little two verse presentation isn't stand alone, you get to verse twenty-three and following:
23 But every man in his own order: Christ the firstfruits; afterward they that are Christ's at his coming. 24 Then cometh the end, when he shall have delivered up the kingdom to God, even the Father; when he shall have put down all rule and all authority and power. 25 For he must reign, till he hath put all enemies under his feet. 26 The last enemy that shall be destroyed is death. 27 For he hath put all things under his feet. But when he saith all things are put under him, it is manifest that he is excepted, which did put all things under him. 28 And when all things shall be subdued unto him, then shall the Son also himself be subject unto him that put all things under him, that God may be all in all.
When Paul preached resurrection, he didn't reduce it to a tweetable nominal number of characters. The resurrected Jesus was the coming Jesus, Jesus the Judge, Jesus the King. In a body, Jesus would deliver up the kingdom to God the Father, put down all rule and authority and power, reign until He puts all enemies under His feet. All things will be subdued to Jesus.
Did Paul merely make known the few words of 1 Corinthians 15:3-4, and that was the gospel? You can't say that. You've got to keep reading and see that the Jesus they received was King. That's why the New Testament authors, the apostles, quoted Psalm 110 more than any other Old Testament text. Their Jesus was the Messiah of the Old Testament, the King, the One Who possessed all authority, and Who would put all under His feet.
The Jesus Paul preached died for sins, but He rose from the dead too. He raised from the dead to fulfill all the other aspects of salvation that should also be and were preached. He saved not just from the penalty of sin, but also from the presence of sin. This same Jesus justified but also would glorify. He would reconcile men through His death, but also through His resurrection, saving them at the moment of their justification, but continue saving them in their sanctification and their glorification.
A reason why so many professing Christians don't live the gospel is because they don't know the gospel. They have their fire insurance, produced through a minimal presentation of Jesus that emphasizes Him as Savior. They didn't get the other part, the offensive part, that would have resulted in their own exclusion and rejection. Now they think they're saved, but they're not.