How do we know the struggle with sin is true for Christians?

Paul's discourse in Romans 7 serves as a definitive evidence of the believer's struggle with sin. He articulates how, despite his desire to do good, he frequently finds himself acting contrary to that desire, indicating the power of sin still at work. This struggle reflects the believer's awareness of their sinfulness and their inability to achieve perfect righteousness by their own means. The presence of such a struggle is exclusive to believers, as only they are sensitized by the Holy Spirit to the reality of sin and motivated to strive for holiness. Thus, the internal conflict expressed by Paul validates the truth of a believer's ongoing battle against sin.