There is a simple, universal or cosmic or existential narrative of the cross—the horizontal beam. Humanity has fallen, every individual person has sinned and must go by way of the cross to gain eternal life. But, for all its merits, this is a theological abstraction. It is not the biblical narrative.
The biblical narrative of the cross is not universal or cosmic or existential and it is nothing like as simple. It is historical—the vertical piece, which sustains whatever else we may wish to say.
It arises out of the story of ancient Israel. The brutal execution of Jesus by the Romans is a critical moment in the story of how the descendants of Abraham made the long and arduous journey from exile to empire, from judgment to justification, from sin to forgiveness, from Law to Spirit, from death to the life of the age to come.