Who is the wretched man that Paul mentions in this passage? In this sermon on Romans 7:13–25 titled “The Wretched Man Identity,” Dr. Martyn Lloyd-Jones concludes his study of this question. He says the person Paul speaks of in this passage is a servant of sin and therefore cannot be regenerate. For all throughout the rest of Scripture, Christians are said to be free from the law and no longer slaves to sin. There is truly freedom in Christ. This cannot be an immature Christian either because all Christians, regardless of maturity, are still in Christ and sanctified in His blood. According to Dr. Martyn Lloyd-Jones, this passage can only be understood as speaking of the unregenerate person that is still in sin and a slave under the law. What does this mean for the Christian life? Dr. Lloyd-Jones says this means Christians are free from the dominion of sin and the law. They are no longer slaves, but children and inheritors. All Christians can live in the power of the Spirit and can know the freedom from sin.

http://www.mljtrust.org/sermons/the-wretched-man-identity-2/