From the Bible’s perspective, the gospel is a word that means “good news.”  It is not a list of do’s and don’ts, or a set of wholesome principles to live by.  The gospel is a public announcement of life-altering news that calls for, even demands, a response.  In ancient times, when another country’s army invaded and took control of the government in your land, the new leader’s messengers would visit every city, town, and village to declare the “gospel” that there is a new king in power.  You could either transfer your loyalty and service to the new regime, or you could refuse to comply and become an enemy of the state.  The Bible’s gospel is that God’s Son, Jesus Christ, is the new anointed king.  His kingdom is God’s kingdom, and he comes to save sinners, set them free from sin’s deadly penalty, and redeem them from all previous regimes that set themselves up against God and his holy kingdom.

One way to explain the gospel is from the “air” by giving a bird’s eye view.  From an air-level vantage point, the gospel is the grand story of Scripture (Creation → Fall → Redemption → Restoration), which is the kingdom of God has arrived in the life, death, resurrection, and ascension of Jesus Christ for our salvation (Mark 1:15; Acts 4:12; 17:22-31; Romans 14:17-18).

Another way to explain the gospel is from the “ground” view.  At this vantage point, simply unpacking God, Man, Christ, and Repentance/Faith helps us understand who God is, who are sinful human beings in relation to God, who Christ is and what his role is in salvation, and what is your proper response to this message (Luke 13:3; Acts 16:30-31; 2:37-39; Romans 10:9-10).

Combining both perspectives on the gospel from the “air” and from the “ground” lends an explanation of the “three-fold” gospel for our “three-fold” problem.  Every single person is born a sinner estranged from loving fellowship with God.  We need a new heart, a new righteousness, and a new holiness in order to be restored to God.  The gospel is the news that God has provided all these solutions totally by his grace to sinners who receive these gifts from God by repentance/faith alone through Jesus Christ alone.