"Gospel" literally means "Good news". This news or message is 'good' because it is the best news. The Gospel of Jesus Christ is what the church centers itself on as its main message. For it is this good news that regenerates, transforms, and sancifies. This Gospel message can be summed up in four parts: God, Man, Christ, Response.
God is the infinite, eternal, holy Creator of all things. He alone is worthy of all praise, honor, and glory. His holiness and righteousness are such that He cannot even look upon evil (Hab. 1:13) and will not leave sin unpunished (Exodus 34:7).
God created men and women in His own image and likeness that all humankind would glorify and enjoy Him by reflecting His character and living a life that in joyful, obediant worship. BUT all humans beings fell in Adam as our representive, and all of mankinds further approval of Adam's choice is in our own willful sinful disobediance against our Creator (Romans 3:9-18). Therefore all mankind is seperated from God by their sin. We are guilty and justly condemned no matter how good we think we are (Ephesians 2:1-3).
Sin is deep and has corrupted everything in us. We do sinful things because we are sinful people living in rebellion against our Creator. God is angry at sinner and His wrath is against us. Therefore we our helplessness and unability to save ourselves. Salvation for mankind must come from outside of ourselves.
God the Father sent His Son to take on flesh in order to bring salvation according to the purposes of His grace. Jesus, the Son of God, lived perfectly obedient to the God and willingly gave up his life as a sacifice for the sins of his people. On the cross, Jesus stood as a subsititute, taking the place of and bearing the guilt, punishment, and curse for them (Gal 3:13; 1 Peter 2:24, 3:18). 3 days after his cruxification on the cross Jesus rose from the dead. His resurrection proved His victory over sin and death (1 Cor. 15:3-4).
Only in Jesus Christ can we have salvation. Now there is a way for us to have a loving, reciprocal relationship with him.
The gospel message always demands a response. Hopeless sinners cannot earn forgiveness by their good works. God commands all people everywhere to turn from their sins and put their trust in Jesus Christ (Acts 17:30; 20:21). First, a person must responsed in repentance - literally "turning away". The sin that seperated us from God is now the sin that we turn away from. Second is called faith. Faith is believing and trusting only in the person and work of Jesus forgiveness of sins. These two ways are the only way that we are to respond to the gospel.