The gospel is the center of the Bible’s theology and the climax of its story. We can define the Gospel as this: the good news of Jesus Christ who died for our sins and rose from the dead as the fulfillment of the promised kingdom of God.
Sin is more than just making mistakes or not measuring up. R.C. Sproul calls sin “cosmic treason.” Our sin is a rebellion against a completely holy and just God. His holiness requires a just response to the sin that we’ve committed. The response that is necessary damns us to eternal torment for our transgressions. This wrath, however, isn’t capricious or unwarranted but rather it is a holy wrath that comes from a perfect God exercising perfect justice. The good news of the Gospel is that Jesus Christ saved us from the wrath that we deserved. His sacrifice on the cross absorbed the just wrath of God that was directed towards us. He became the sin of the world so that those who would believe in Him would be saved. He not only paid the debt of sin that we owed but He also credited to us His righteousness. So we were not only absolved of guilt but we were bestowed the perfect righteousness of Christ.
Our response to the Gospel is simple: we repent and believe. Jesus says in Mark 1:14-15, “the time is fulfilled, and the kingdom of God is at hand; repent and believe in the gospel.” The gospel involves repentance. We turn from sin and towards Christ. We are sorrowful for the damage and rebellion of sin, this creates repentance, or an active turning from sin. The Gospel also involves belief. It's not mere intellectual assent, however; it's a belief that is all-encompassing. We believe the Gospel in our every day lives. Christ’s sacrifice not only paid our debt but also gave us His righteousness as well. We live the remainder of our days daily believing in Christ’s work in our hearts and trusting that He will finish what He started (Phil 1:6; Jude 24-25).
The Gospel drives us to repentance, faith, obedience and gratitude that shapes the way we live our lives, interact within our relationships, and directs our ambitions. The Gospel is not the door we walk through to salvation but it’s the path we walk upon until we meet Jesus face to face.