The Gospel in short:

Everyone has disobeyed God. The One who made us said, "Love the Lord your God with all your heart and with all your soul and with all your mind," (Matt. 22:37) yet we do not and we show it by our actions.

God has declared the punishment for disobedience is eternal separation from Him in a place of everlasting torment. Jesus describes it as a place "where there will be weeping and gnashing of teeth." (Matt. 13:50)

That's the bad news. All people are under the wrath of God. But there is good news (that's what "gospel" means). Jesus came and obeyed perfectly. He then died on the cross, undeserving of death. He took the punishment we all deserve. When we stop trusting in our own "good" deeds and trust the sacrifice that He made, God promises He "will forgive us our sins and purify us from all unrighteousness." (1 John 1:9)

Bad News: we all stand condemned.
Good News: Hope in Christ