The gospel is the Christian message of salvation. Gospel itself means good news - and it is the good news of what God has done through Jesus Christ to rescue us from sin and reconcile us back to himself. This requires just a little unpacking, so below is five steps that lead to an understanding of the gospel. It goes like this: God, Man, Jesus, Response, and Cost
God is the good, wise and loving Creator of all things. He made everything good and for a good purpose. Ultimately everything was created for him which means that everything was created to reflect his goodness and purposes. God is full of amazing love (John 3:16). He is also holy and just and because of this he punishes all evil and removes it from his presence (Romans 1:18).
Human beings are God's highest creation as we are made in the image of God (Genesis 1:27) and made to find our purpose in fellowship with him. But we sinned and in rebellion turned away from God (Isaiah 53:6), preferring other things to him (Romans 1:23). The result of our sin is alienation from God (Isaiah 59:2) and the penalty of our sin is death (Romans 6:23).
Jesus Christ is eternally God, but became a human being to reconcile us back to God. Jesus lived a life of perfect obedience to God (1 Peter 2:22, Philippians 2:8). He died as a substitute, taking our place on the cross, bearing the death penalty that we deserved (Romans 5:8). Jesus then rose again on the third day and is still alive today (1 Corinthians 15:3-4) in order to give us a brand new life both now and forever (2 Corinthians 5:17, John 10:10).
Since the gospel is the good news about what Jesus Christ has already done, you can't do anything to make it happen - it is news of what has already happened. However, the gospel does require a response. The bible says our response must be to repent, believe, and receive. First, we must repent which means doing a U-turn in regards to sin or to turn away from sin (Matthew 4:17). Then we must believe that Jesus died on the cross to forgive our sin (1 Corinthians 15:3), to restore relationship with God, and that he rose again from the dead (Romans 10:9). Finally, we must receive Jesus Christ personally as Savior and Lord intending to obey him (Revelation 3:20).
The gospel is a free gift and the only thing we can do is receive it as a gift (Ephesians 2:8-9). It does, however, come at a high cost to God - it cost him the life of Son Jesus Christ (1 Peter 1:18-19). So we are called to a life of discipleship which means following Christ in obedience (Matthew 28:19-20).