John Nelson Darby emphasizes the distinction between the old man and the new man in Christ, asserting that while the old man represents our sinful nature, we are responsible for our actions through the power of Christ. He critiques the notion that one can excuse sinful behavior by attributing it solely to the old man, insisting that we must recognize our personal responsibility in the presence of sin. Darby argues that the flesh, which opposes the Spirit, is a current reality that must be acknowledged, and that true freedom in Christ involves actively mortifying the deeds of the body. He clarifies that while the old man is considered past in a theological sense, the struggle with the flesh remains a present challenge for believers. Ultimately, he calls for a deeper understanding of our identity in Christ and the ongoing battle against sin.