The gospel is the good news about what Jesus Christ has done to reconcile sinners to God. Here's the whole story:
1. The one and only God, who is holy, made us in his image to know him (Gen. 1:26-28).
2. But we sinned and cut ourselves off from him (Gen. 3; Rom. 3:23).
3. In his great love, God sent his Son Jesus to come as king and rescue his people from their enemies - most significantly their own sin (Ps 2; Luke 1:67-79).
4. Jesus established his kingdom by acting as both a mediating priest and a priestly sacrifice - he lived a perfect life and died on the cross, thus fulfilling the law himself and taking on himself the punishment for the sins of many (Mark 10:45; John 1:14; Heb. 7:26; Rom. 3:21-26, 5:12-21); then he rose again from the dead, showing that God accepted his sacrifice and that God's wrath against us had been exhausted (Acts 2:24, Rom. 4:25).
5. He now calls us to repent of our sins and trust in Christ alone for our forgiveness (Acts 17:30, John 1:12). If we repent of our sins and and trust in Christ, we are born again into a new life, an eternal life with God (John 3:16).
Now, that's good news. A good way to summarize this good news is to biblically unpack the words God, Man, Christ, Response.
1. God: God is the creator of all things (Gen. 1:1). He is perfectly holy, worthy of all worship, and will punish sin (1 John 1:5, Rev. 4:11, Rom. 2:5-8).
2. Man: All people, though created good, have become sinful by nature (Gen. 1:26-28, Ps. 51:5, Rom. 3:23). From birth, all people are alienated from God, hostile to God, and subject to the wrath of God (Eph. 2:1-3).
3. Christ: Jesus Christ, who is fully God and fully Man, lived a sinless life, died on the cross to bear God's wrath in place of all who would believe in him, and rose from the grave in order to give his people eternal life (John 1:1, 1 Tim. 2:5, Heb. 7:26, Rom. 3:21-26, 2 Cor. 5:21, 1 Cor. 15:20-22).
4. Response: God calls everyone everywhere to repent of their sins and trust in Christ in order to be saved (Mark 1:15, Acts 20:21, Rom. 10:9-10).
(Some of this material has been adapted from The Gospel and Personal Evangelism by Mark Dever, p. 43)