The model shift involves moving from a Roman law court setting to a family love, adoption, and reconciliation setting. Instead of a payment made by the Son to satisfy the wrath of an offended Father, the cross is viewed as the inevitable cost of loving. God is love, and love always gets hurt. We can hold back from getting hurt, or we can go through Gethsemane to accept the sacrifice that is involved in loving. Since the Son was already loving and being hurt by our sin in the OT, he is the Lamb slain from the foundation of the world. As John said "Behold the Lamb that keeps taking away the sin of the world" (a present tense). So grace is not a payment made in a few hours on Good Friday to satisfy the wrath of God. Grace is the costly sacrifice of loving, which is part of the eternal Lambness (as Lamb of God) of the Son.
This moves the atonement from a mere three hours on Good Friday to the very heart of God. The cross is therefore not a payment to satisfy the wrath of the Father but a visible expression in space and time of the eternal sacrificial love of God. This also means that we can enter into the fellowship of his sufferings (sacrificial love). That is not possible if he alone is the once and for all substitutionary sacrifice.
The word ransom (Mark 10:45) also changes focus from the amount paid to the freedom of the one who is ransomed. Genuine love cares about the freedom of the other. So the purpose of the atonement is not making it possible for us to be forgiven (love does that anyway) but making it possible for us to enjoy the glorious liberty of the children of God. And God's holiness is not to condemn but with a view to our eventual perfection. This is worked out in the Commentary on Romans.. The Greek Orthodox understanding of diakaiosune (as opposed to the Latin idea of law court justification) is also set out in the articles "Does Romans Need Justification" and "Did Paul Teach Justification".
We all agree that God is holy, but the holiness of love is not a necessity to condemn sinners to eternal damnation but the intention by all means and at great cost to perfect them for his heaven. One liberal view of the atonement is the moral influence theory which means that we are changed by the example of Christ's sacrifice. I prefer to say we are saved by grace alone and neither our forgiveness or transformation is in any way dependent on our goodness or moral efforts. To my mind what is wrong with the evangelical theology which I learned is that Trinitarian nature of God. It suggests that the Father can only begin to love when the Son has made a payment to satisfy his justice, and the Holy Spirit can only begin his work in us when we have accepted that payment. I prefer to say that the Father has always been a loving parent who delights to welcome sinners into his family with a view to their perfection in heaven. The Son has always been Lord and Servant, Shepherd and Lamb, Friend and Healer, etc. And the Spirit has always been Ruakh as Wind lifting and moving, Wind inbreathing, and Wind burning. Humans, however ignorant and imperfect, have always had access to Him. The art is to set our sail to let him move us, open our hearts to inspiration, and let him warm us as we gather at the family hearth.
So the three Persons of the Trinity are involved in our at-one-ment
but in different ways. And we each can experience God in a different sequence.
Some first get to know the Father as a little child, some come in through
experiencing forgiveness and new direction through the Son, and some first
experience the inspiration of the Spirit. This is why among thousands of
new charismatic songs you will find very few that require a substitutionary
payment to be accepted before we can experience the Spirit. There is the
strong substitution involved in any kind of loving, but the model is not
seen as a payment in a Roman law court. Wrath is therefore a sub-section
of the love of God.