The Gospel is good news. But, for the Gospel to be the good news, you have to understand that there are bad news.
Here is a bad news. God, He is the Creator. The Creator of you, me, everyone and everything in the world. That means that we are accountable before Him. We have to give an account as to how we live our lives. We are created for the purpose of having a loving relationship with Him and to rule the rest of the Creation by His ways.
Here is another bad news. Our ancestors, Adam, has rebelled against God. This makes the rest of us, his descendents, also rebelled against God. Instead of living by a loving relationship with God, we turned to live for ourselves.
"For although they knew God, they did not honor him as God or give thanks to him, but they became futile in their thinking, and their foolish hearts were darkened. Claiming to be wise, they became fools, and exchanged the glory of the immortal God for images resembling mortal man and birds and animals and creeping things." Romans 1:21-23
Even worse news. Because we did not honor God, God has placed His judgment upon all of us. The judgment is that we are guilty of sinning against God.
"Therefore God gave them up in the lusts of their hearts to impurity, to the dishonoring of their bodies among themselves, because they exchanged the truth about God for a lie and worshiped and served the creature rather than the Creator, who is blessed forever! Amen.
For this reason God gave them up to dishonorable passions. For their women exchanged natural relations for those that are contrary to nature; and the men likewise gave up natural relations with women and were consumed with passion for one another, men committing shameless acts with men and receiving in themselves the due penalty for their error.
And since they did not see fit to acknowledge God, God gave them up to a debased mind to do what ought not to be done. They were filled with all manner of unrighteousness, evil, covetousness, malice. They are full of envy, murder, strife, deceit, maliciousness. They are gossips, slanderers, haters of God, insolent, haughty, boastful, inventors of evil, disobedient to parents, foolish, faithless, heartless, ruthless. Though they know God's righteous decree that those who practice such things deserve to die, they not only do them but give approval to those who practice them."
- Romans 1:24-32
Therefore, because God is good. He has to punish sinners. The punishment for sins is death and everlasting judgment. This is what we deserve.
Unless you can say and prove that you have loved God with all your heart, soul, mind, and strength by being constantly faithful, obedient, and loving to Him without fail, you have transgress against God.
God is just and He will punish those who transgress against Him.
However, this is the good news. The Gospel:
But now the righteousness of God has been manifested apart from the law, although the Law and the Prophets bear witness to it— the righteousness of God through faith in Jesus Christ for all who believe. For there is no distinction: for all have sinned and fall short of the glory of God, and are justified by his grace as a gift, through the redemption that is in Christ Jesus, whom God put forward as a propitiation by his blood, to be received by faith. This was to show God's righteousness, because in his divine forbearance he had passed over former sins. It was to show his righteousness at the present time, so that he might be just and the justifier of the one who has faith in Jesus. - Romans 3:21-26
God showed that He is just and merciful by sending His Son, Jesus Christ, to die for our sins and raised for our righteousness. By repenting of your sins and trusting in Jesus Christ, you will received forgiveness for your sins and made justified before God.
This is foretold in the Law and the Prophets.
Isaiah 53 (ESV)
Who has believed what he has heard from us?
And to whom has the arm of the Lord been revealed?
For he grew up before him like a young plant,
and like a root out of dry ground;
he had no form or majesty that we should look at him,
and no beauty that we should desire him.
He was despised and rejected by men;
a man of sorrows, and acquainted withbgrief;
and as one from whom men hide their faces
he was despised, and we esteemed him not.
Surely he has borne our griefs
and carried our sorrows;
yet we esteemed him stricken,
smitten by God, and afflicted.
But he was pierced for our transgressions;
he was crushed for our iniquities;
upon him was the chastisement that brought us peace,
and with his wounds we are healed.
All we like sheep have gone astray;
we have turned—every one—to his own way;
and the Lord has laid on him
the iniquity of us all.
He was oppressed, and he was afflicted,
yet he opened not his mouth;
like a lamb that is led to the slaughter,
and like a sheep that before its shearers is silent,
so he opened not his mouth.
By oppression and judgment he was taken away;
and as for his generation, who considered
that he was cut off out of the land of the living,
stricken for the transgression of my people?
And they made his grave with the wicked
and with a rich man in his death,
although he had done no violence,
and there was no deceit in his mouth.
Yet it was the will of the Lord to crush him;
he has put him to grief;
when his soul makes an offering for guilt,
he shall see his offspring; he shall prolong his days;
the will of the Lord shall prosper in his hand.
Out of the anguish of his soul he shall see and be satisfied;
by his knowledge shall the righteous one, my servant,
make many to be accounted righteous,
and he shall bear their iniquities.
Therefore I will divide him a portion with the many,
and he shall divide the spoil with the strong,
because he poured out his soul to death
and was numbered with the transgressors;
yet he bore the sin of many,
and makes intercession for the transgressors.
And that is what the good news is. By repentance and faith in Jesus Christ, you will not perish but receive everlasting life, and being put back in the right relationship with God.
For God so loved the world (You) that He gave His only Son, that whoever believes in him should not perish but have eternal life. 17 For God did not send his Son into the world to condemn the world, but in order that the world might be saved through him. 18 Whoever believes in him is not condemned, but whoever does not believe is condemned already, because he has not believed in the name of the only Son of God. 19 And this is the judgment: the light has come into the world, and people loved the darkness rather than the light because their works were evil. 20 For everyone who does wicked things hates the light and does not come to the light, lest his works should be exposed. 21 But whoever does what is true comes to the light, so that it may be clearly seen that his works have been carried out in God.” - John 3:16-21