How do we know that salvation is through Christ's crucifixion?

The certainty of our salvation through Christ's crucifixion is grounded in Scripture, particularly in Romans 5, which teaches that through one man's obedience, many are made righteous. This underscores the sacrificial nature of Christ’s death; He didn't merely die; He died for us, taking upon Himself the iniquities of us all, as stated in Isaiah 53. Furthermore, when the Apostle Paul emphasizes that we are justified through faith in His blood, he signifies that it is not human action or our belief itself that saves us, but the object of our faith—Christ crucified. Thus, our assurance lies not in our performance, but in the perfect, redemptive work Christ accomplished on the cross.