The Gospel is the “Good News” that what we could never do, Jesus did perfectly. God has made a way for us.
God’s perfection, justice, reign demanded complete obedience to His Law. Because our representative, Adam, failed to obey God, he and all mankind fell completely and from then on we are all born with sin in our hearts of stone. (Rom. 1:18 & 19, Rom. 5:12, Rom. 3:10-12, Ezekiel 36:26)
God came down and rescued his people. By sending his son, Jesus the Christ, to become fully human, to live a life void of any sin, and then to to be completely submitted to doing the will of his Father, Jesus was crushed for our transgressions and all of Gods wrath was poured out on him and every sin of the elect was atoned for. We who believe in our hearts and confess with our mouths are seen by God as righteous because we are covered in Christ’s blood. Propitiation is the exchange of our unrighteousness and sin with Christ’s righteousness with the result being that we are justified and God’s wrath fully satisfied. (Rom. 3:23-26, Matt. 11:27, John 6:44)
The Gospel is not about living our best life, bettering ourself or even WWJD. The Gospel is all Christ and how He left His kingdom and heavenly throne, came down as a helpless baby, lived a perfect life despite temptation, took the complete punishment of our sin on the cross, died and was resurrected before returning to Heaven.
Just like Adam and Eve tried to cover up their sin with fig leaves, we too try to hide our sin and deal with it ourselves. Fig leaves just don't cut it. God had to come and cover his children with skins from an animal. What a picture of what He was about to do in giving his own beloved son.