The Law and The Gospel

"The law of God shows us what God commands (which, of course, is good) but the law does not possess the power to enable us to do what it says. You could put it this way: the law guides but it does not give. The law shows us what a sanctified life looks like, but it does not have sanctifying power. It's the gospel (what Jesus has done) that alone can give God-honoring animation to our obedience. The power to obey, in other words, comes from being moved and motivated by the completed work of Jesus for us. So, while the law directs us, only the Gospel can drive us." - Tullian Tchividjian