Here we are warned about the wrong way to follow Jesus. If you remember back to Matthew, some of Jesus’ biggest opponents were the Pharisees. Paul had been one of those. He believed a relationship with God was earned by following rules. Here he warns followers of Jesus not to go back to that way of thinking. So, in chapter 6, he let us know we are dead to sin, and in chapter 7 he tells us we are dead to rule-following too. The hard thing about rule-following is that it only makes us aware of how bad we are and even causes us to desire the forbidden things even more. We won’t be given the right answer until chapter 8.
Trying to be a good Christian by following rules is a common mistake. It brings about failure and guilt. In those who do a reasonably good job of following the rules, it brings about pride and judgment of others. Find a Christian who feels defeated in his or her relationship with Jesus and you probably have found someone who is basing their relationship with Jesus on rule-following.