This text defines the gospel. If the gospel is lost, perverted or corrupted then there is no biblical church nor can one be a Christian. This is the primary truth of the Bible, the church, and the Christian.
In this sermon, a definition of the gospel is given then defended from the text.
The gospel is the foundational Christian message, by which God's people are being saved, that describes Christ's death for our sins, his burial, and his historical, eye-witnessed resurrection.