The gospel begins by asserting that you are by nature an enemy of God because of your sin. The Bible defines sin as those thoughts or actions that do not measure up to what God requires. God requires us to live lives of generosity, humility, thankfulness, compassion and the like at all times and without fail. Instead, we by nature live lives of gossip, or of greed, or of boasting, or of envy, etc. We by nature fall short of what God requires of us and are therefore worthy of eternal judgement. You may not be as bad as you could be, but neither are you as good as what God requires. You cannot save yourself from your sins, neither can you save yourself from the judgement that sinners deserve.
The gospel then proceeds from telling you who you are to what God did. While you by nature are an enemy of God, God sent Jesus Christ to die on a cross in order to make enemies of God friends of God. Jesus is the only way to be made right with God, for Jesus is the only one God has provided to save sinners. When Jesus died on the cross, he died as a substitute for all who believe in him. He received the judgement that sinners deserve in order to set sinners free from their sin and the judgement to come. Then God raised him from the dead, for he was satisfied with the substitutionary death that he died on behalf of all who believe. Jesus' death and resurrection grants forgiveness to all who believe, making them right with God. Jesus' death and resurrection also transforms those who believe, causing them to live lives worthy of the forgiveness they have received.
The gospel calls us to turn away from our sins which destroy us and to turn to Christ, the only one who can save us. The gospel calls enemies of God to become friends of God. If you believe that you are good enough, then go your own way. The gospel is not for you! But if you believe that you are in desperate need of the forgiveness and transforming power of Christ, then come as you are. The gospel is for you!