Mercy is not getting what we deserve. Matthew 18:21-35 tells parable of a servant under so much debt he is entirely without means to satisfy it. His master has mercy on him and forgives the debt. This is what God does for us. He knows that our sin has brought us to an impossible spot and he knows we can't find our way out. God's mercy gives us life, and he charges us to share that mercy so those who are still stuck in their sin can see the hope that the Father has for them in Jesus Christ.