Why is the presence of sin still a concern for believers?

Believers in Christ feel the ongoing presence of sin in their lives, which causes a constant internal battle. Romans 7:21 explains that even though we have been set free from sin's dominion, the struggle remains real; sin is still present in our flesh. This conflict highlights our continual need for God's grace and mercy, as seen in Peter's encouragement to believers in 1 Peter 2:11 to abstain from fleshly lusts that war against the soul. Ultimately, recognizing sin's presence helps believers understand their reliance on Christ for ongoing strength and victory.