“For I passed on to you as most important what I also received: that Christ died for our sins according to the Scriptures, that He was buried, that He was raised on the third day according to the Scriptures, and that He appeared to Cephas, then to the Twelve.” ‭‭1 Corinthians‬ ‭15:3-5‬ ‭HCSB‬‬

How did Paul learn the gospel? How did he get saved? Most of us know the story, but for these who do not here, you go.

“Falling to the ground, he heard a voice saying to him, “Saul, Saul, why are you persecuting Me? ” “Who are You, Lord? ” he said. “I am Jesus, the One you are persecuting,” He replied. “But get up and go into the city, and you will be told what you must do.”

So Ananias left and entered the house. Then he placed his hands on him and said, “Brother Saul, the Lord Jesus, who appeared to you on the road you were traveling, has sent me so that you can regain your sight and be filled with the Holy Spirit.”

‭‭Acts‬ ‭9:4-6, 17‬ ‭HCSB‬‬

https://www.bible.com/72/act.9.4-6,17.hcsb

I believe Saul, later God changed his name to Paul, heard the gospel through some of his Christian prisoners. But God appeared to him directly to present the gospel. Between the time of God talking to him on the road to Damascus and Ananias healing his eyesight He was praying and I do believe God was talking to him. Within a few years, He disappeared into the wilderness for three years. While he was there I do believe God changed Paul’s whole theology of who He and Jesus are.

So the Gospel is Jesus died. Was buried. Raised on the third day. And appeared to the disciples and Peter.

The gospel is the death, burial, and resurrection of Jesus Christ. No other religion can submit proof of their messiah accomplishing all three. They can submit proof of one maybe two, But only Jesus has come back to life and stayed alive. Every other religious leader has a grave we can visit and is filled with there bones. But Jesus' grave is still empty. As it was 2,000 years ago.

Without the resurrection of Jesus, all our belief in Him would be pointless (1 Corinthians 15:17). And we would still need to sacrifice sheep and cows to cover our sins for one year as the Old Testament Jews had to.

But we have a savior who paid the sins once for all that way we may live for Him who sits at the right hand of God.

“For Christ also suffered for sins once for all, the righteous for the unrighteous, that He might bring you to God, after being put to death in the fleshly realm but made alive in the spiritual realm.

Now that He has gone into heaven, He is at God’s right hand with angels, authorities, and powers subject to Him.”

‭‭1 Peter‬ ‭3:18, 22‬ ‭HCSB‬‬

https://www.bible.com/72/1pe.3.18,22.hcsb