The most fundamental elements of the gospel are:
1. God really does exist.
2. Jesus Christ came and died for the sins of all humanity.
3. God's offer of salvation is open to everyone.
Whoever you are, wherever you live, whatever you do, whatever bad you may have done (but now repent of and turn away from), you can be saved. That is the offer and the promise of the gospel.
The four "gospel" books - Matthew, Mark, Luke and John - are not themselves the gospel. They are eyewitness reports of Jesus' own words explaining the gospel. The gospel message is then continued through the rest of the New Testament.
The gospel is indeed the best news that our world has ever had. It is the map to the road of life. It shows us The Way.
Fact Finder: What did Jesus say we are to do with the gospel?
(a) think about it (b) read it (c) tell others (d) believe it
Mark 1:15