As the Apostle Paul said, “For there is one God, and one mediator also between God and men, the man Christ Jesus (1 Timothy 2:5). My Reformation Study Bible, ed. by R.C. Sproul, Sr., (Nashville, TN: Thomas Nelson, 1995) offers an exposition upon “Christ the Mediator” (p. 1910). Therein it notes:
The saving ministry of Jesus Christ is summed up in the statement that He is the “Mediator between God and men” (1 Tim 2:5). A mediator is one who brings together parties who are out of communication and who may be alienated, estranged, or at war with each other. The mediator must have links with both sides, so as to identify with and maintain the interests of both, and represent each to the other on a basis of goodwill. Thus Moses was the 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 in “enmity against God” (Rom. 8:7), standing under God’s wrath, the punitive rejection whereby as Judge he expresses active anger against our sins (Rom. 1:18; 2:5-9; 3:5, 6). Reconciliation of the alienated 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; c.f. 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 peace for us (Eph. 2:16-18; Col. 1:20). Peace here means an end to hostility, guilty, 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 peace with God (Rom. 5:1; 10). The mediators 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 the 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 guilt of sin (Heb. 9:11-10:18).