How do we know Christ's death was necessary for salvation?

Christ's sacrificial death is portrayed in the New Testament as the fulfillment of God's justice. In Matthew 26:52, Jesus rebukes Peter for using a sword, emphasizing that those who rely on the sword will perish by it. Instead, Christ willingly submitted to the law and its penalties to redeem those who could not uphold it (Isaiah 53:5). His suffering under the sword of justice—not just human violence but the divine requirement for sin—shows that grace is offered through His atoning sacrifice (John 3:16). Without His death, our transgressions remain unforgiven, and the law condemns us all. Hence, His death was not only desirable but necessary for our salvation.