But before I lay it out, let me first say what I believe are the criteria that any plausible account of the Atonement must meet. (1) First, something of great importance to humanity was achieved by Christ's death, and any plausible account of the Atonement must say just what this is. Here of course one will likely say that Christ's death made possible (or inevitable as we universalists would say) humanity's salvation. This is no doubt so, but of course a word is not itself the explanation we seek. If we say that Christ's death made possible our salvation, we must then explain just what we mean by "salvation". (2) Second, any account of the Atonement must explain the necessity of Christ's death. What Christ achieved, He achieved (at least in part) through His death; and what was achieved by His death could not have been achieved in any other way. (3) Third, any account of the Atonement must explain how Christ's death achieved its effect.
So then we need these three things: an account of the what, an account of the necessity of the what, and an account of the how.
Here's my idea. (I'm certain that it's not new. It - or a variant of it - comes to us from Schliermarcher.) I begin with a number of propositions that seem to me axiomatic to the Christian world-view. Sin brought about a rupture, a breach that separates God from man. The purpose of the Incarnation was to heal that breach. The breach consists is a lack of love, both for God and for neighbor; and thus the purpose of the Incarnation was to perfect love.
Let us then view the Atonement through the lens of this idea. It was a bottom an expression of love, and in that love God makes possible the perfection of our love. How was his done? As Christ told us, there is no greater love than a love that will sacrifice all for another. This fact is known by all. Thus if Christ were to "give His all" for us, and if we knew that He and the Father were one, we could know that God's love for us is unsurpassable. But if we knew this - if we knew that the author of our being loves us with an unsurpassable love - we would inevitably begin to return that love. But to the degree that that love is returned, the breach between God and man is healed.
Here then is our What and our How. The Atonement achieves a perfection of love, and it does so by the natural human propensity (no doubt implanted in us by God) to return love that is given to us. But what of the necessity of the What? How might we prove that God could achieve the perfection in no other way than the sacrifice of Christ? I do no see my way clearly here, but I suspect that we must draw upon our capacity for free will. A perfect love is a love freely given; it is a love that is not forced. But how might one lead another to love if one cannot force that love? One can do no better than reveals one's true nature and hope that this touches the other deeply. But what is God's true nature? It is love. Thus God had no choice but to make known his perfect love for us. How best to teach this lesson? How bestfor God to make known His love? By the most perfect expression of that love, and this I contend comes in self-sacrifice. In any other act, one might suspect that the motives are ultimately selfish. But in self-sacrifice - a sacrifice that ends in death on the cross - there can be no such suspicion. The very nature of deliberate sacrifice of a life rules out the motive to serve only the self.
This is my view of the Atonement. It was not a price paid. It was a love displayed. It does not ransom us. It calls forth from us the perfection of love for which we were made.