How do we know that the doctrine of Christ's substitutionary atonement is true?

The truth of Christ's substitutionary atonement is deeply embedded within the Bible, particularly through the typology of the Old Testament sacrifices, including the Passover lamb. Matthew 26:20 reminds us of the solemn moment when Jesus shared the Passover with His disciples, directly linking His impending crucifixion to the fulfillment of the sacrificial system established in Exodus 12. Here, the lamb's death is not just a historical event but a divine ordinance prefiguring Christ, the ultimate Lamb, whose sacrifice would undertake the sin of the world (Revelation 13:8). Furthermore, the completeness of His work is encapsulated in John 17:4, where Jesus declares, 'I have finished the work which thou gavest me to do,' affirming the doctrine's significance and truth.