One of the most importan ideas in religious hisotry

The supremely important fact in early Christian history is the
development of the concept of "The Church" as an independent,
self-existing, metaphysical entity. This metaphysical entity was
conceived as embodying itself in the whole body of believers; living,
dead, and yet to be born. The entity was eternal, indestructible, and in
its essence immutable. Although partially embodied in a visible society
its essential being was conceived as independently sustained in the
nature of the universe. It was an idea in the strict Platonic sense. No
concept like this is found in the contemporary pagan cults. Even the
Jewish concept of the 'chosen people' is ethnic or national rather than
purely religious and it has no tinge of that metaphysical existence
which is the most notable element in the Catholic concept of the Church.
The elements out of which 'the Church' concept was constructed were
four: two Roman, one Greek and one Hebrew. The Roman lawyers, in the
process of fitting a municipal legal system to a world empire, evolved
the twin legal entities, 'state' and 'sovereignty.' These entities were
endowed with divers qualities; eternity, immutability, etc., but
especially with the quality of having existential reality apart from any
individual embodiment thereof. Greek philosophy contributed the idea of
the Cosmopolis, the ideal world-city in which the fullest development of
human personality was to be attained. This concept was as purely
metaphysical as the self-existing, absolute 'state' of the Roman law,
but unlike the Roman concept it had no concrete existence. The Jewish
contribution was that of the 'chosen people,' 'the elect nation.' These
four concepts were transferred from their original loci to the Christian
society. The fact that all of these concepts were combined and centered
on the same social group and the further fact that each of these
concepts supplemented the others in a remarkable way resulted in the
formation of one of the most powerful ideas in religious