But in your hearts honor Christ the Lord as holy, always being prepared to make a defense to anyone who asks you for a reason for the hope that is in you; yet do it with gentleness and respect, (1 Peter 3:15)
What is the Gospel?
Simply put, the Gospel is the 'Good News' of Jesus Christ concerning His provision for humanity's sin problem.
According to 1 Corinthians 15:3-4, it is... "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."
The Gospel According to God by John MacArthur