Mark 1:14,15 Now after that John was put in prison, Jesus came into Galilee, preaching the gospel of the kingdom of God, And saying, The time is fulfilled, and the kingdom of God is at hand: repent ye, and believe the gospel.
Jesus is the fulfillment of every bible prophecy regarding His virgin birth and incarnation from Genesis to Zechariah. He is The Christ, The Son of God, the Savior of the world. And with His first advent, He announced that the kingdom of God is near. The proclamation that Jesus is the Christ and that the kingdom of God is near is the gospel. The gospel of Jesus Christ and His kingdom is not a good idea, it is good news!
But note that Jesus said to those with ears to hear that they need to repent and believe the gospel. Repent and believe, not accept and receive. Good news is only good news for those who understand the bad news. All mankind since Adam are born into this world sinners by nature and by choice. In that condition, we are separated from God. We are incapable and unable to redeem ourselves. By turning away from our sins and placing faith in the perfect sacrifice of Jesus Christ for my sins, I become a part of the family of Christ and a citizen of the kingdom of God.
Reader, repent and believe the gospel, and you shall be saved.