What is the Gospel?
The gospel is good news about bad news. The bad news is that every person is sinfully flawed in their nature and dead in their sin before a perfect and infinite creator God (Rom. 3:9-18, 23; Eph. 2:1). The good news is that God, being rich in mercy, sent Jesus to live perfectly, die as a substitution, and resurrect victoriously over sin and death (1 Cor. 15:1-11). The atonement Jesus made for sin is enabled by God’s grace through the power of the Holy Spirit and the atonement is applied by our response of repentance and faith (Acts 20:21). We cannot by our good works earn favor with God (Eph. 2:8-9). It is by grace through faith that we are made a new creation to live to righteousness (2 Cor 5:17; Eph 2:4-8; 1 Pet 2:24, Ephesians 2:10).
To summarize: God is perfect. You and I are hopelessly separated from God by our sin. Jesus is our only hope to have a relationship with God. You must turn from your sin and follow Jesus by faith alone, otherwise, you will perish.
The gospel is the living story that Jesus can turn your infinitely bad situation into eternally good news for God’s glory.