Why is the doctrine of substitutionary atonement important?

Substitutionary atonement is a core tenet of the Reformed faith, emphasizing Christ's role as our substitute. It teaches that Jesus took upon Himself the sins of His people and faced the punishment that we deserved. As preached in 1 Peter 2:24, 'Who his own self bare our sins in his own body on the tree,' this truth enriches the understanding of grace and justice in salvation. Without substitution, humanity remains lost, as sin requires atonement. Thus, the assurance of salvation rests in the completed work of Christ, who satisfied God's justice and redeemed believers through His sacrifice, affirming the doctrine that 'salvation is of the Lord' (Jonah 2:9).