The gospel, in a nutshell is:
The world, and man were created by an infinitely wise, loving and righteous God. Man, through the disobedience of Adam became bound by sin to a mortal life of rebellion against the justice of God.
Because God will not lay aside His justice, sin must be met with wrath, and so Man who dies in his sin must thereby be damned. Just as God’s love is infinite and absolute, so also is His justice, and because He is the source of all life, which He created for His own good pleasure, to live in sin is to commit the greatest of crimes, for in so doing we offend the very Maker of all that exists.
God, in His mercy, however, chose to satisfy the demands of His justice by becoming a man sent to redeem the world by His own blood. Through Jesus Christ, the forgiveness of sin and restoration to fellowship with God were made available to us, if we confess and believe that Jesus is LORD and that God raised Him from the dead.
If indeed we believe this to be so, we must then also believe that we have lived against God’s law, and the only rational response is to REPENT, that is, to turn away from our sin and toward God in a total surrender to the Lordship of Christ. (Acts 2:38) The baptism mentioned in Acts is a ceremonial washing for consecration to the priesthood of God, which marks us as no longer our own, and longer the servants of sin, but as having been redeemed, consecrated to the service of God.
It is this surrender that brings the Holy Spirit into the life of the believer to comfort, accompany, strengthen, and guide the believer in all truth, and to preserve him in the faith until Christ returns or the believer after death is gathered unto Him in everlasting life.