What is the Gospel? It is the true Easter message

The Resurrection of Christ

Now I would remind you, brothers, of the gospel I preached to you, which you received, in which you stand,  and by which you are being saved, if you hold fast to the word I preached to you—unless you believed in vain.

For I delivered to you as of first importance what I also received: that Christ died for our sins in accordance with the Scriptures, that he was buried, that he was raised on the third day in accordance with the Scriptures.

1 Corinthians 15:1-4