Most people already know that the word gospel means, "good news." But what is that good news? The good news aspect of the gospel is that Christ's obedience has secured eternal justification for sinners who will believe in him. That's a mouthful, but every bit of that statement means something!
Let's begin with the idea of Christ's obedience. The Bible says of Christ, "And being found in fashion as a man, he humbled himself, and became obedient unto death, even the death of the cross." (Philippians 2:8) We learn from the scripture that God took on a body and became a man in order to perfectly fulfill God's law. Christ was completely obedient to his heavenly Father! In fact, he said, "And he that sent me is with me: the Father hath not left me alone; for I do always those things that please him." (John 8:29) Christ was obedient to the will of his heavenly Father from the beginning of his life and extended to the death of the cross.
Christ was perfectly obedient so that he could die the death of sinners and suffer the wrath of God that rightfully belonged to them. If you recognize that you are a sinner, then you should understand that this is very good news indeed!
The Bible teaches that every person is born dead in trespasses and sins. Every person enters into this life as a sinner and it is evidenced by the fact that we sin. We choose to lie, covet, lust, to be angry for selfish reasons, and to prefer our own good over the good of others. Our sins reveal that we are sinners. God is rightfully angry with sinners. As a God who loves and gives life, he is angry when people choose things that tend to death and not life and he is justly angry when we are selfish and self-serving. None of us do the will of God naturally and so we are deserving of God's vengeance.
Maybe you think God is harsh to punish sinners for their sin. Consider two things:
Firstly, God is holy and cannot allow sin into his presence. And if God let sinners with their sin into his holy presence, then heaven would become just like earth with all of the death and suffering that sin brought along with it. A good God will not allow sin to contaminate his eternity.
Secondly, everything God demands from us (sinless perfection) he provided in his Son, Jesus Christ.
There's a gospel chorus that says,
He paid a debt he did not owe;
I owed a debt I could not pay;
I needed someone to wash my sins away.
And now I sing a brand new song: Amazing Grace the whole day long!
Christ Jesus paid a debt that I could never pay!
The grace of God means he puts the needs of others (even his enemies) above his own comfort. God's perfect and holy law allowed for a perfect spotless sacrifice to take the place of sinners and suffer their deserved punishment. But no person matched God's holy standard except for God himself. That is why the God of love and justice took on a body and lived a perfect life - so he could die our death on the cross.
God calls every man now to repent - to turn to him from your wrong ideas about sin and God and eternity - and believe his gospel. To believe that God did for you the thing you could never do for yourself and trust him to save you. God gives us salvation from our sins and from his wrath.
It's possible for you to hear the gospel, understand it, and reject it or do nothing with it. But eternity with God is only available through the finished work of Jesus Christ on the cross.