How does Paul describe the battle within believers?

In Romans 7:19-21, Paul articulates his frustration, stating, 'For the good that I would, I do not; but the evil which I would not, that I do.' This describes the duality of the believer's nature: while being renewed in Christ, they struggle against the remnants of sin that exist within them. Paul emphasizes that this internal conflict underscores our need for Christ's redemptive work, reminding us that the law reveals our sins but offers no power to overcome them. This demonstrates that human effort is insufficient without divine assistance and grace.