Why is Jesus' death significant for Christians?

The significance of Jesus' death lies in its role as the ultimate once-for-all sacrifice for sin. According to Christian doctrine, He took upon Himself the sins of the world, receiving the punishment that we deserve in accordance with God's justice. This act of substitutionary atonement means believers are justified and declared righteous, not because of their own works, but through faith in Christ's finished work. His death opens the door to grace, eternal life, and fellowship with God, making it the cornerstone of the Christian faith.