Keeping the Law became quite a monumental task for the observant Jew. I'm sure even the most devout found themselves wishing for a way to be free from the bondage of the Law. Surely God could come up with a better way to enable us to be right with Him!
Paul picks up that idea in Romans 7, and equates the rule of the Law over humanity to the law of marriage. As long as I am bound to my wife, I am not free to go bind myself to someone else. In order to be free from the marriage vow, one of the spouses has to die. (My wife informed me that if I tried to get "bound" to someone else while she was alive, the death of one spouse could easily be arranged!) Once one of the parties is dead, the law no longer binds the other.
In order for us to be free from bondage to the requirements of the Law, we have to die to it. In Jesus Christ, we have indeed been put to death in relation to the Law, and now we are bound to Him. Our old relationship is gone, and we have a new life in Christ.
What difference does this make in our life? It changes the effect the Law has on us. Where once we were condemned under the Law, and bound to keep every little part of it, now the Law simply shows us what God expects of us. We aren't left on our own trying to obey God, as we were when we were "under Law," but are now empowered by the Holy Spirit.
Paul stresses this in verse 6, where he tells us that now "we serve in the new way of the Spirit, and not in the old letter of the law." (HCSB) The paragons of Jewish piety in Paul's time were the Pharisees (Paul, of course, having been one himself). They kept the Law, the interpretations of the Law, and the side details of the interpretations of the Law. They were "letter" people, who saw righteousness as an external reality, based on how well you could follow the rules. They looked good, but they had not had a change in their heart or in their relationship to God.
In Christ, we are set free from that kind of observance. The Holy Spirit enables us to obey God not to make ourselves righteous, but as a result of being made righteous in Christ. Our relationship to God is not based on what we do, but on what Jesus did for us. We are released from the power of sin through the cross of Jesus, and now given the power of the Spirit as children of God.
As those set free from the tyranny of the Law, now belonging to Jesus Christ, we have the ability in the Spirit to bear fruit for God. We no longer serve ourselves, but Him. Our lives now show the reality of Jesus as we live to honor Him. This change not only impacts us, but those we meet every day. As we live out our new life, our new relationship, and our new power, we will show the way Christ can change lives, and be a witness to a world that needs to hear that such a change is possible.