Gospel means "good news". This is the message of the Story we read from Scripture, from Genesis through Revelation. It is the Story of creation, fall, redemption, new creation. It is a Story of a love that will not let us go, and that would have everyone repent and believe this good news.
God in Christ comes, becomes one of us- fully human. To bruise, or crush the serpent's head, to take our death on himself- paying the penalty for our sins by his death on the Cross. Resurrected to new life so that all who put their faith in him can begin to know this new life even now and forever. Ascended to the right hand of the Father, so that the Holy Spirit can be poured out on those who believe, so that they can be a witness. And to return so that what has begun now in Jesus, in God's kingdom coming to earth in him, can be completed and fulfilled, in all its glory.
This must begin with each one of us. There is a law in ourselves that we can't escape. We would like to, but we can't. We know that how we live and how we ought to live are more often than not, two different things. It does no good to say that, "No one can be perfect." That's true. But beside the point, here.
The point is that we don't measure up to what we know is right and good. We are special as human beings, created in God's very image. Yet we have departed from living accordingly, and violate what we know to be true. We often neither do the good we should do, or refrain from doing what we shouldn't.
The remedy for us is Jesus Christ. He is the perfect image of God, and by faith in him we are being renewed back into that image. This involves getting back to what we were created for, in the first place. For relationships, with God and with each other. For good work, doing what God has designed for each one of us to do, in our unique, God-given capacities.
The gospel is good news, and it's an ongoing good news for us all. That there's forgiveness for our sins, that we're not left to ourselves and the dead end ways we take. All found in Jesus.
See this excellent post: Is Our Gospel Too Small? from Bob Robinson.