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

The necessity of Christ's death stems from the reality of human sinfulness, as stated in Romans 3:23: 'For all have sinned and come short of the glory of God.' This inherent sin nature means that without the shedding of blood, there is no remission of sins (Hebrews 9:22). The sacrifice of Christ on the cross fulfills God's justice as He punishes sin while simultaneously extending mercy to His elect. The crucifixion reveals that God's holiness demands a penalty for sin, and only through the offering of His Son could this penalty be satisfied, ensuring that His people could be reconciled to Him.