How does Christ's righteousness affect believers?

According to Ephesians 1:4, believers have been chosen in Christ before the foundation of the world to be holy and blameless in God's sight. This emphasizes that their righteousness is not self-derived but is imputed through faith in Jesus Christ. The fulfillment of the Law by Christ gives believers a new identity as they are seen as righteous before God, not because of their own works but because of His righteousness. Such a standing provides assurance of salvation and eternal security, reinforcing the doctrine of justification by faith alone, as celebrated in the Reformed tradition.