The Lord Jesus Christ is the only one who can make us right with God and in order for this to happen two problems must be overcome, our sin and God’s wrath. This means that if we are to be saved from both, salvation must be accomplished through judgement. Christ is our substitute, but too often the images we have of substitutes (from team games or films, which some use to illustrate what happened on the cross of Christ) often simplify the act of substitution into error. These next four questions in the Heidelberg Catechism address the importance of Christ as our substitute. “Why must he be truly human and truly righteous?”, “Why must he be truly God?”, “And who is the mediator – true God and at the same time truly human and truly righteous?” and “How do you come to know this?”
The necessity of human nature
Since God’s justice demands that human nature, which has sinned, must pay for its sin; but a sinner could never pay for others. Because of this, God the Father, who so loved the world, sent his son to die on the cross receiving the judgement of God in the place of fallen man. Therefore, we can understand why Christ must become truly human and understand why the incarnation of Christ leads to the death of Christ because the justice of God demands that human nature pay for its sin.
Understanding the above allows us to see why many modern illustrations of substitution are not sufficient or accurate in representing what Christ actually accomplishes. For instance, imagine a judge has a case before him where the wronged party (a family of a murdered man) is waiting to see what judgement will be handed down to the murderer. Just before the sentence is given an innocent man offers his life in place of the murderer, he offers himself as a substitute, willing to receive the judgement. If the judge judged this man he would be committing a crime, because to judge an innocent man would be wrong according to what is just, it would not be a just judgement according to the law. How then does God justly justify the unjust?
Salvation through Judgement
The Cross of Christ accomplishes salvation through judgement and since the wronged party is God himself, he alone must forgive if we are to be forgiven. Therefore, Christ who is truly God becomes truly human, so that we can be saved through the giving of his life, to bear the weight of God’s anger in his humanity and earn for us and restore to us righteousness and life. On the cross we see the great exchange, “for our sake he made him to be sin who knew no sin, so that in him we might become the righteousness of God” ( 2 Cor 5:21). Because God cannot justly judge an innocent man, Christ was made to be sin, though he knew no sin, so that we might become righteous through this great exchange on the cross, where Christ was judged in our place. In Christ our sin and guilt is removed (Expiation) and Christ was the sacrifice of atonement (Propitiation). We are bought with a price from the curse of the law (Redemption) and we are restored in our relationship with God (Reconciliation).
We deserved to be punished for our sin against God but God so loved the world that he sent his son that whoever believes in him should not perish but have eternal life (John 3:16). Jesus is the one who bears our sins and receives the penalty we deserved. God poured his wrath on his son and the righteousness of Christ is imputed to us by faith. Therefore, we understand why our saviour, who is our substitute must be both truly God and truly human.
The good news
The Gospel is the power of God unto salvation to everyone who believes, to the Jew first and also the Greek (Rom 1:16). The Gospel is the good news about Jesus Christ and his accomplishment in both the old and new Testaments. The Gospel is what we go and tell because faith comes by hearing and hearing through the word of Christ (Rom 10:17). This is how we come to know of Christ and his accomplishment, it is how we come to know the only true comforter, the only mediator, the only substitute, the only truly righteous person, the saviour.