From Jurgen Moltmann’s “The Trinity and the Kingdom: The Doctrine of God”:

The cross is at the center of the Trinity….No Trinity is conceivable without the Lamb, without the sacrifice of love, without the crucified Son.

And from “The Crucified God: The Cross of Christ as the Foundation and Criticism of Christian Theology”:

If one conceives of the Trinity as an event of love in the suffering and the death of Jesus — and that is something which faith must do — then the Trinity is no self-contained group in heaven, but an eschatalogical process open for [all] on earth, which stems from the cross of Christ.