What does the Bible say about the war within believers?

In Romans 7, the Apostle Paul articulates the inner conflict experienced by believers, noting that even when he desires to do good, evil is present within him. This struggle is indicative of the ongoing battle between the flesh, which is corrupted by sin, and the spirit, which strives to fulfill God's law. As Paul declares, 'I find then a law that when I would do good, evil is present with me' (Romans 7:21). This illustrates that true believers experience a dichotomy where they embody both a desire for righteousness and an inclination toward sin, reflecting the complexities of their salvation and ongoing sanctification.