The Gospel simply means 'Good News'. Your debt has been paid and you're free to go!
But in order for this to be good news we need to understand that there is a problem in our lives that needs to be solved, or a debt we have incurred that needs to be settled, and on both counts - it was! Jesus has solved the problem AND paid the debt we owe to God ... in full!
Let's break this down -
The bad news is -
We have a sin debt and the penalty for such a debt is the death penalty.
The good news is -
Jesus came into the world and was crucified. The death He died was for us in order to pay the debt we owe to God. After He died He was buried AND three days later He rose again! And If that is not enough good news, here is some more - He is coming back again one soon day just for all those who have believed or trusted in Him. Now that is good news in a world with nothing but bad news!