How do we know that Christ's death secures our salvation?

The assurance of salvation through Christ's death lies in the doctrine of imputation, as explained in 2 Corinthians 5:21 and Romans 4:6. Christ took upon Himself the sins of His people, becoming legally responsible for them, while His perfect righteousness is imputed to believers. This means that when God looks at His people, He sees them clothed in the righteousness of Christ. Moreover, Christ’s declaration that it is finished in John 19:30 signifies that He completed the necessary sacrifice once and for all, leaving nothing for us to contribute to our salvation. Thus, believers can have full confidence that their salvation is secure in Christ alone.