How do we know that sin is a problem for Christians?

Paul articulates in Romans 7 that every believer experiences an inner conflict due to the presence of sin that dwells in them. This is not merely an external battle but an internal struggle where sin influences thoughts and actions contrary to God’s law. The very existence of this struggle is a clear indication of one's regeneration; for without being born again, there would be no awareness of sin or desire for righteousness. This awareness and conflict serve to confirm that sin is indeed a serious problem that affects the believer's life.