Mercy and grace

Perhaps a month or two ago I heard my Pastor in youth group mention the difference between mercy and grace. "Mercy" he said "is something we get that we deserve or expect. Grace is something we get that we don't deserve." I tried at that moment to picture a judge in court giving a sentence to a prisoner who was convicted of first degree murder. Normally a judge is considered merciful for sentencing the man to a lifetime in prison rather than capital punishment. Firstly I ask myself if he got what he deserved, and I believe so. A lifetime in prison, never to go out and experience the joys of the world is punishment enough. However, I also ask myself what grace would be in that situation. Absolute freedom, no punishment at all. 'What?' we ask ourselves. 'He deserves to be punished; he deserves to learn a lesson for what he did!' Yeah I agree. But it's the same thing with us.
We murder through our hate, commit adultery through our lust, steal, lie, cheat, shout profanities, and think terrible thoughts. And if God were merciful, he would sentence us all to a lifetime in Hell, away from the joy of experiencing Him in all of His wonder. We deserve it. But He chose grace. He paid our punishment through Jesus so we could get off Scott free. We may not think it's fair, and it isn't. But He loved us enough to be unfair.
I remind myself of that truth everytime I mess up, because every time I wonder why God let's all this great stuff happen in my life despite how horrible I have been and how much I have done wrong. This thought that I can't understand keeps me going. More

The beauty of grace is that it makes life not fair. -Relient K

But by the grace of God I am what I am, and his grace to me was not
without effect. No, I worked harder than all of them--yet not I, but the
grace of God that was with me. 
1 Corinthians 15:10