What is the good news of Christianity for us? The good news is God. God is Creator, Judge, Christ, and King.
Creation. God created you and this world out of the overflow of his love for and joy in himself: Father, Son, and Holy Spirit. He created so that his people would share in this love and joy in himself, in his glory. Jesus spoke of his glory, "which [God had] given [him] because [God] loved [him] before the world's foundation" (John 17.24).
Humanity. So God created the world in 6 days. On the 6th day he created humans in his own image so that they would enjoy him in this world and reflect him. God created us out of the overflow of his love and joy!
26 Then God said, “Let us make man in our image, according to our likeness. They will rule the fish of the sea, the birds of the sky, the livestock, the whole earth, and the creatures that crawl on the earth.”
27 So God created man in his own image;
he created him in the image of God;
he created them male and female.
28 God blessed them, and God said to them, “Be fruitful, multiply, fill the earth, and subdue it. Rule the fish of the sea, the birds of the sky, and every creature that crawls on the earth.”
They would reflect him by ruling over the world, reproducing to multiply and fill the earth, and resting from work. In this three-fold way they would display God and enjoy God and know God's glory in this world. God created them for this. This was the highest privilege in all of creation. It is also a great responsibility with matching accountability.
Condemnation. We humans rebel against God. We sin against him. Sin is always a personal attack against God (even though it can be more than this it is never less). Adam and Eve ate the fruit in the Garden of Eden and chose to reject God as their joy and love. Instead they decided to use God to enjoy and reflect themselves apart from God. Because God is the judge, he condemns them to eternal death because that is the penalty for sin. "The wages of sin is death" (Rom 6.23). Adam and Eve were cursed and kicked out of the dwelling place of God where there is blissful blessing.
Righteousness. God is not a cranky judge who lashes out on humans who are guilty of tiny infractions. God is a righteous judge. When we say God is righteous we mean that he is "unswervingly committed to his glory." God is committed to his love by displaying his glory for his people and protecting that glory from attack. "Is God unrighteous to inflict wrath? Absolutely not! Otherwise, how will God judge the world?" (Rom 3.5-6). God is righteous to inflict wrath because he is the judge who executes perfect justice upholding his glory for his people to enjoy in his world. So, God is committed to his love by displaying his glory for his people and protecting it from attack. God punishes sin because it is the right thing to do.
So as sinners we deserve the condemnation and curse of a righteous God committed to love because we have violated his love and his glory. We are condemned to hell and to death. This is not good news for us.
But here is the good news…
Incarnation. God, because of his infinite and uncontainable love (1 John 4.8; John 3.16), sent his Son Jesus into the world to become fully human while remaining fully God. "The Word was with God and was God . . . and the Word became flesh and dwelt among us" (John 1.1, 14). God the Son became a man, born of the virgin Mary. He lived a completely righteous life on this earth never sinning.
Substitution. He lived a perfect life he did not deserve to die. Yet, he willingly goes to the cross to die on the cross for sinners, in their place. God condemns Jesus on that cross in the place of sinners. Jesus gave his life as a ransom for many (Mark 10.45). He died in darkness under God's judgment and cries out, "My God, my God, why have you forsaken me?" (Mark 14.34-35). God forsook Jesus on the cross. He was a propitiation, the sacrifice of atonement, the wrath-bearer for our sins. He substituted for sinners. He took his people's place. This is the supreme demonstration of his love for his people (Romans 5.8).
Invitation. God raised Jesus from the dead on the third day. Jesus took up his life again. Jesus is the King. God now calls and invites you to repent from your sin and your righteousness and instead trust in Jesus as your King, Lord, and Savior. This is true whether it is initial trust in conversion from non-Christian to Christian or continual trust as a Christian. You are called by God to repent from your sin and your righteousness and instead trust in Jesus as your King and Savior. "If you confess with your mouth, 'Jesus is Lord,' and believe in your heart that God raised him from the dead, you will be saved" (Rom 10.9). Jesus says, "Repent and believe in the gospel" (Mark 1.15). God is calling you to repent from your sins and believe in Jesus.
Restoration. If you will trust in Jesus you will receive (or continue to enjoy) forgiveness of all your sins. You will be reconciled to God in a right relationship with him, accepted by him. You will receive a share among God's people (Acts 26:18), and you will receive his Holy Spirit who will begin to transform you at the point of initial trust all the way into eternity. He will transform you as you enter into the kingdom of Jesus Christ the King. In this, you will do works worthy of true repentance (Acts 26.20).
This is the gospel. God created the world out of the overflow of his love and joy because he's the creator. Because man sinned, God is the judge who condemns and curses sinners because of their sin in order to uphold his glory and love for his people. But God sent his Son, Jesus the Christ into the world to become fully human while remaining fully God to substitute himself for us with his life, death under God's curse and condemnation, and resurrection from the dead. Now Jesus is the King, not just the divine King but the human King. God calls you to repent from your sin and righteousness and trust in Jesus as your King, Lord, and Savior. All those who do will be restored receiving forgiveness of sins, a share among God's people, and the gift of God's Holy Spirit who will begin to transform them now into eternity. So do the works worthy of repentance to show that your "faith" and "repentance is real and true.
 John Piper's definition: http://www.desiringgod.org/messages/the-freedom-and-justice-of-god-in-unconditional-election
 God demonstrates his "righteousness" in pouring out his wrath on Jesus in passing over other sins (Rom 3.25).