"Now we know that the law is good, if one uses it lawfully"1 Timothy 1:8
It seems that every few years there is a fight over keeping the 10 commandments in the public square (a courthouse, a public school, etc.). I'm not interested in getting into the merits of the arguement for either position here, but I do find it sadly ironic that many Christians are ready to fight for the 10 commandments to be lifted up in the public square, but are much less motivated to see the gospel take center stage. It is as if some think that the law of God is a cure-all. That if we can just gather ourselves around the law things will change: our cities, our citizens, our culture. And, this is not only a social/political issue. Many of us are also tempted to think this way as it relates to our own growth in the grace of godliness. It is as we think that the law of God is our cure-all. That if we can just gather ourselves around the law we will change: our thoughts, our hearts, our lives.
But law does not save you. The law cannot save you. This does not mean the law is bad. The law is holy, just and good. The law cannot save you, but it is still the gift of God. God's law is a gift that shows us his way, our rebellion, and our great need for the gospel. The law deals a crushing blow to our sense of self-righteousness, but also prepares us for the good news of God's forgiving and restoring grace. In the law we see God's standard of righteousness, but in the gospel we see Jesus fulfilling all righteousness for us. Here are the two gifts: one that exposes our guilt, and another than unleashes God's grace; one that crushes, and another that revives and renews. The law is good when used rightly--not to justify--but to show our need for justification that must come from outside of ourselves.
No, the law does not save, but it does help us to savor the gospel.
Relevant Read: Christless Christianity, by Michael Horton