For God did not send His Son into the world to condemn the world, but that the world through Him might be saved. “He who believes in Him is not condemned; but he who does not believe is condemned already, because he has not believed in the name of the only begotten Son of God.” John 3:17-18
Jesus said: “Repent, and believe in the gospel.” Mark 1:15b
The Gospel in a Nutshell
The bad news: We are ALL sinners and ALL of us deserve Hell!
"For all have sinned and fall short of the glory of God." Romans 3:23.
"Do you not know that the unrighteous will not inherit the kingdom of God? Do not be deceived. Neither fornicators, nor idolaters, nor adulterers, nor homosexuals, nor sodomites, nor thieves, nor covetous, nor drunkards, nor revilers, nor extortioners will inherit the kingdom of God." 1 Corinthians 6:9-10
"But the cowardly, unbelieving, abominable, murderers, sexually immoral, sorcerers, idolaters, and all liars shall have their part in the lake which burns with fire and brimstone, which is the second death.” Rev 21:8
The good news: God sent His only Son to be the sacrifice for our sins. Jesus took our place on the cross. He took the punishment that we deserve. The sinless Son of God took our sins upon Himself so that we could be forgiven and granted eternal life.
"But God demonstrates His own love toward us, in that while we were still sinners, Christ died for us." Romans 5:8
"For God so loved the world that He gave His only begotten Son, that whoever believes in Him should not perish but have everlasting life." John 3:16
"For the wages of sin is death, but the gift of God is eternal life in Christ Jesus our Lord." Romans 6:23
“Believe on the Lord Jesus Christ, and you will be saved...” Acts 16:31
For more see: So...What is the Gospel?