(I can't think of a better time to start posting again about my model of the Atonement than Easter, so here goes...)
The Father pours out His wrath upon the Son on Good Friday.
This statement, while accepted by most evangelicals as true, is very disturbing until we have a clear understanding of the nature and purpose of wrath. If wrath is seen as an expression of hostility and hatred, then the Cross must be seen as an event of hostility of the Father against the Son. Such a Trinitarian dynamic is contrary to all orthodox Trinitarian thought and must be rejected, for Trinitarian theology asserts that the Father is ever and always acting in love toward the Son.
Therefore, the wrath that the Father pours out upon the Son on the Cross must be an expression of the Father's love for the Son.
But how is that the case? Wrath, as we commonly think about it, is an expression of hostility and hatred. But Biblically, that is not the only form that wrath takes. While wrath can be a knife that wounds, it can also be a scalpel that cuts away cancer. Wrath can be a fire which destroys, or it can be a crucible that purifies. Throughout the Old Testament, God pours out His wrath on the Israelites by sending other nations to crush her. He does this not out of hostility; He does this because He wants them to repent and turn back to Him. So He purifies them down to a remnant and repentance blossoms. His wrath is not a tool of animosity, it is God's way of loving His rebellious people.
Objective models of the atonement will talk about how the cross "changes God's attitude toward sinful man". But there is no change in attitude here. God ever and always wants a spotless bride for His Son, and His purifying wrath is part of how He achieves that. Before the Fall, God loved Humanity. After the Fall, God loved fallen Humanity but wanted Humanity to be pure. And thus He pursued Humanity in His purifying wrath, but Humanity fled from the ordeal of wrath (in much the same way a person with a cavity avoids the dentist). And it is just as well, for Humanity could not survive such wrath for we are nothing but a "lump of perdition", after all the sin is burned away in the crucible of God's wrath, nothing would remain.
God, wishing to purify us, but knowing that we cannot survive such wrath, sends His Son to suffer the wrath for us on the Cross. Alone, Christ has no impurities to burn out of Him. But we are perichoretically united with Him on the Cross through the Holy Spirit. Our impurities are now His for we are now in Him (and Him in us). When He is punished, when He experiences God's wrath, when He is purified, we are too--in Him.
This is (one reason) why I insist that the penalty is one of Union, not Substitution. For if we are "spared" of the penalty, then we are "spared" the purification, for they are one and the same.