In 1 Corinthians 15:3–8, Paul articulates the main points of the gospel
 that he preached to the Corinthians (1 Corinthians 15:1). He describes the gospel as something he received
 and then delivered
 to them. This recalls 1 Corinthians 11:23 where, referring to the Lord’s Supper, he states that he received from the Lord
 the teachings that he delivered
 to the Corinthians.
In both instances Paul is most probably speaking of direct revelations that he received from God. This is confirmed in Galatians 1:18: I did not receive it [the gospel] from any man, nor was I taught it, but I received it through a revelation of Jesus Christ.
Paul summarizes the gospel in four main points, each point introduced with the word that.
 The first point is that Christ died for our sins in accordance with the Scriptures.
Christ
 is a title that points to Jesus Christ’s official role. The Old Testament (which Paul refers to as the Scriptures
) foretells the death of the Christ for the sins of God’s people. One can point to specific prophecies, such as Psalm 22:1–31 and Isaiah 53:1–12. At the same time it should be remembered that the whole Old Testament speaks of Christ (Luke 24:26–27).  
The phrase for our sins
 is repeatedly used by Paul (Romans 5:8; Romans 8:32; Galatians 1:4; Ephesians 5:2; Titus 2:14). It indicates that Christ’s death was a substitutionary death. He died the death that our sins deserved.
3 For I delivered to you as of first importance what I also received: that Christ died for our sins in accordance with the Scriptures,