When I first came to faith I was taught to define the atonement as “at-one-ment” because through the atonement we are one with God. Soon, I was taught to move on in my understanding by developing an elaborate doctrine of atonement. I was then able to choose the right “theory” of atonement.
I now know that we cannot understand atonement by definitions and theories. We must rather focus fully on Jesus himself as the atonement. Even then, we do not really grasp the atonement because it is mystery just as Jesus himself is mystery. But we can never even begin to understand the atonement by focusing on concepts rather than Jesus himself as atonement.
The atonement is truth that we are to understand, but it is the truth of this unique person who is himself the truth of our oneness with God. Jesus is the true God moving faithfully towards us in history to make our tragic cause his own. Simultaneously, he is also the true man moving faithfully towards God on behalf of us all. In this movement oneness with God “happens”.
This same Jesus comes to us personally by his Spirit revealing who he is as the truth of oneness. We cannot know the truth by any other way. For truth is this unique person who is the actual oneness of God and humanity. Only as he opens to us who he is in living encounter do we know the truth of oneness with God. Then Jesus, the truth, lives in us and we live in the truth. That is the only way we understand something of the mystery of “at-one-ment”.