How do we know that Jesus' death was necessary for our salvation?

Jesus’ death serves as the crucial event that establishes the New Testament, as outlined in Hebrews 9:15. This verse highlights that a significant covenantal transition occurred through His death, enabling the redemption of transgressions from the first covenant. The death of Christ represents the ultimate sacrifice that fulfills the requirements set forth in the Old Testament sacrificial system, where types and shadows could only hint at the reality to come. His death was essential for enacting the will of God, providing believers with eternal inheritance and the promise of salvation.