Thanks so much for this important question.
In essence, Jesus' gospel is simply: That all men and women are in reality the sons and daughters of God, and that by faith each one may come to realize and daily experience this ennobling truth.
Always the burden of his message was: the fact of the heavenly Father's love and the truth of his mercy, coupled with the good news that man is a faith-son of this same God of love.
The Urantia Book, (132:4.1)
Of course "the gospel," as it has come down to us through the centuries, has had different meanings and different concepts attached to it. We have prepared a topical study on the Gospel, comparing the traditional sources and informations with the newer revelation of the Gospel as taught by Jesus in The Urantia Book. You might like to take a look at that, and see where the two correspond and/or contrast