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

As stated in Romans 5:10, 'For if, when we were enemies, we were reconciled to God by the death of his Son, much more, being reconciled, we shall be saved by his life.' This indicates that the death of Christ is not just a historical event but a vital component of God's salvific plan. His death serves as a substitute for sinners, fulfilling the requirements of God's justice while expressing His mercy. The atoning sacrifice of Christ brings reconciliation, ensuring that those who believe are justified and can have peace with God, fundamentally securing their salvation.