How do we know Christ was our substitute?

Substitutionary atonement is a doctrine rooted deeply in Scripture, revealing that Christ suffered in the place of His people. Isaiah 53 clearly states, 'Surely he hath borne our griefs and carried our sorrows; he was wounded for our transgressions' (Isaiah 53:4-5). By bearing the iniquities of His people, Christ fulfilled the requirements of God's justice, ensuring that they would not suffer the eternal separation from God that sin incurs. This is seen in how Christ's cry of abandonment reflects His unique position as substitute, absorbing the wrath of God so that His people could be reconciled. His suffering was not universal, but rather specific to those whom the Father had given Him, thus affirming the necessity of belief in the gospel for the assurance of salvation.