Why was Christ a mediator between the Father and us?
Thus Moses was mediator between God and Israel (Gal. 3:19), speaking to Israel on God's behalf when God gave the law (Ex. 20:18-21 ) and speaking to God on Israel's behalf when Israel had sinned (Ex. 32:9-33:17). Every member of our fallen and rebellious race is by nature "hostile to God" (Rom. 8:7), standing under God's wrath, the punitive rejection whereby as Judge He expresses active anger at our sins (Rom. 1 :18; 2:5-9; 3:5, 6).
Reconciliation of the alienated parties is needed, but can only occur if God's wrath is quenched and the human heart, that opposes God and motivates a life against God, is changed. In mercy, God sent His Son into the world to bring about the needed reconciliation. It was not that the kindly Son acted to placate the harsh Father; the initiative was the Father's own. In Augustine's words, "in a wonderful and divine way even when He hated us, He loved us" (Commentary on John 110.6; ct. John 3:16; Rom. 5:5-8; 1 John 4:8-10).
In all His mediatorial ministry the Son was doing His Father's will (see "The Humble Obedience of Christ" at John 5:19). Objectively and once for all, Christ achieved reconciliation for His people through penal substitution. On the cross He took our place, carried our identity as it were, bore the curse due to us (Gal. 3:13), and by His sacrificial shedding of blood made peace for us (Eph. 2:16-18; Col. 1 :20). Peace here means an end to hostility, guilt, and exposure to the retributive punishment that was otherwise unavoidable-in other words, forgiveness for all the past, and eternal, personal acceptance for the future.
Those who have received reconciliation through faith in Christ are justified and have peace with God (Rom. 5:1, 10). The Mediator's present work, which He carries forward through human messengers, is to persuade those for whom He achieved reconciliation actually to receive it (John 12:32; Rom. 15:18; 2 Cor. 5:18-21 ; Eph. 2:17).
Jesus is "the mediator of a new covenant" (Heb. 9:15; 12:24), the initiator of a new relationship of conscious peace with God, going beyond what was known under the Old Testament arrangements for dealing with the guilt of sin (Heb. 9:11-10:18). One of Calvin's great contributions to Christian understanding was his observation that