In the 4th Century, the founding idea of catholicism was to create unity through a singular organizing ideology. Over time, this singularity led to organizing hierarchically. Unity came through a single power structure.
This vision of forced unity through order is of the same substance as Pax Romana: that the Roman Empire could force peace by conquering the world. Which is, charitably, not the best example of being “one” with others.
What is interesting to me is how clearly our understanding of unity seems to require order. That we can’t conceive of a “one” that comes through diversity. Our very definitional sense of oneness is functionally inseparable from sameness. Otherwise we require a comprehensive structure that compels our mutuality.
I suspect that the Spirit is guiding us toward a one that doesn’t assume these things. We just can’t comprehend how it would work.