The Gospel Jesus Preached Is Different than What Most Have Been Taught

Before Jesus was crucified and resurrected, He went around preaching a message from God—a message of good news. Yet, that message is very different from what many have heard today!
What was the good news Jesus proclaimed? Did He only preach about His coming sacrifice for the world? Was He telling people to just accept Him in their heart?
Did He simply tell people to believe in Him? Or was it far more than that? What was the gospel Jesus preached?