"In God's Word we hear both law (commands to be obeyed) and gospel (good news to be believed). The perennial temptation of the church in every age is to confuse these two words.
Sometimes the law is dissolved into the gospel; more frequently, the gospel becomes absorbed into the law. We often hear calls to "live the gospel" or even to "be the gospel." In effect, this means that our own conformity to the righteousness that God demands becomes the message, rather than Christ's life, death, and resurrection. When God speaks his law, we finally have a true measure of our lives. There is no room for excuses. We have all fallen short of the glory of God, not only in what we have done but in what we have failed to do.
Yet when God speaks his gospel, it is a strange and surprising announcement. Although God could justly condemn all of us, he has planned and executed our redemption at the greatest personal cost: the suffering of his own Son.
In the fullness of time, the Son became flesh. He fulfilled all righteousness during his life, in our place, and then bore our curse and was raised on the third day as the glorified head of his body, the church. All of our righteousness, holiness, and redemption are found in Christ alone; and because he lives, we too will be raised in glory beyond the reach of sin and death.
The law promises life on the condition of perfect obedience; the gospel promises life in Christ alone, through faith alone. Only in Christ can any sinner dare to stand unashamed before the face of God." [via]