The Heart of Substitution

The concept of substitution may be said to lie at the heart of both sin and salvation. For the essence of sin is man substituting himself for God, while the essence of salvation is God substituting himself for man. Man asserts himself against God and puts himself where only God deserves to be; God sacrifices himself for man and puts himself where only man deserves to be. Man claims prerogatives that belong to God alone; God accepts penalties that belong to man alone. 

If the essence of the atonement is substitution, at least two important inferences follow, the first theological and the second personal. The theological inference is that it is impossible to hold the historic doctrine of the cross without holding the historic doctrine of Jesus Christ as the one and only God-man and Mediator. Neither Christ alone as man nor the Father alone as God could be our substitute. Only God in Christ, God the Father’s own and only Son made man, could take our place. At the root of every caricature of the cross there lies a distorted Christology. The person and work of Christ belong together. If he was not who the apostles say he was, then he could not have done what they said he did. The incarnation is indispensable to the atonement. In particular, it is essential to affirm that the love, the holiness and the will of the Father are identical to the love, the holiness and the will of the Son. God was in Christ reconciling the world to himself.

- John Stott, The Cross of Christ
Vitamin Z