Through Augustine, Martin Luther, and others, God has brought the heart of the Christian faith, the gospel message , back into focus over and over again. The gospel messageis the good news of what Jesus Christ did for us!
Pastor Tim Keller of Redeemer Presbyterian Church in Manhattan, New York wrote in his book The King's Cross that the central difference between the Christian faith and other religions is this: All other religions focus on what the person must do and hope that their actions allow them to be with God.
On the other hand, the good news of the Christian faith is: This is what was done for you. Jesus Christ lived for you on this earth and died for you so that the way to God is free.
The gospel message is a joyful and liberating message!
The gospel message is that God enters into a relationship with you, not on the basis of what you have done or accomplished (or not done/not accomplished), but on the basis of what Jesus Christ has done for you in His death on the cross and in His resurrection.