What does the Bible say about the struggle against sin?

The struggle against sin is a recurring theme throughout the New Testament, particularly in the writings of Paul. In Romans 7, Paul describes the inner conflict of doing what he hates and not doing what he desires—a clear depiction of the battle every believer faces with their sinful nature. This conflict exists because the believer is simultaneously justified and being sanctified; while their old self has been crucified with Christ, the remnants of that sinfulness continue to tempt and challenge them. Paul encourages believers to take an active role in this struggle by mortifying the deeds of the flesh and seeking to live according to the Spirit. The presence of this internal conflict is actually evidence of regeneration, indicating that a new life has begun and that a believer is engaged in the spiritual warfare that accompanies their faith.