What does the Bible say about the old and new man?

The apostle Paul writes extensively about the conflict between the old man and the new man in passages such as Romans 7, highlighting the believer's dual nature. The old man represents our sinful flesh, which is at enmity with God and struggles continually against the Spirit. On the other hand, the new man is created in righteousness and true holiness, which empowers believers to serve God despite the ongoing battle with sin. This distinction illustrates the complexity of the Christian experience, where believers are called to 'put off the old man' and 'put on the new man' (Ephesians 4:22-24) as they grow in grace.