The apostle Paul declared that he was determined to know nothing save Christ and Him crucified. This was the apostle's way of emphasizing the extreme importance of the Cross to Christianity. The doctrine of the Atonement is central to all Christian theology. Luther called Christianity a theology of the Cross. The figure of a cross is the universal symbol of Christianity. The concept of atonement reaches back to the Old Testament where God set up a system by which the people of Israel could make atonement for their sins. To atone is to make amends, to set things right.
Both the Old and New Testaments make it clear that all human beings are sinners. As our sins are against an infinite, holy God who cannot even look upon sin, atonement must be made in order for us to have fellowship with God. Because sin touches even our best acts, we are incapable of making a sufficient sacrifice. Even our sacrifices are tainted and would require a further sacrifice to cover that blemish, ad infinitum. We have no gift valuable enough, no work righteous enough to atone for our own sins. We are debtors who cannot pay their debts.
In receiving the wrath of the Father on the cross, Christ was able to make atonement for His people. Christ carried, or bore, the punishment for the sins of human beings. He atoned for them by accepting the just punishment due for those sins. The Old Testament covenant pronounced a curse upon any person who broke the law of God. On the cross, Jesus not only took that curse upon Himself, but He became "a curse for us" (Galatians 3:13). He was forsaken by the Father and experienced the full measure of hell on the cross.
Orthodox Christianity has insisted that the Atonement involves substitution and satisfaction. In taking God's curse upon Himself, Jesus satisfied the demands of God's holy justice. He received God's wrath for us, saving us from the wrath that is to come (1 Thessalonians 1:10).
A key phrase in the Bible regarding the Atonement is the phrase, "in behalf of." Jesus did not die for Himself, but for us. His suffering was vicarious; He was our substitute. He took our place in fulfilling the role of the Lamb of God who takes away the sin of the world.
While the Father's wrath is real, it should be noted that the atonement Christ made was not a case of the Son working against the Father's will. It is not as if Christ were snatching His people out of the Father's hand. The Son did not persuade the Father to save those whom the Father was loathe to save. On the contrary, both Father and Son willed the salvation of the elect and worked together to bring it to pass. As the apostle Paul wrote, "God was in Christ, reconciling the world to Himself" (2 Corinthians 5:19).