From “Catholic Consciousness: The Anthropological Implications of the Dogma of the Church” by Vladimir Lossky. English translation (from the French original) in St. Vladimir’s Seminary Quarterly, Volume 14, No. 4, 1970.
No differences of created nature — sex, race, social status, language, or culture — can affect the unity of the Church; no divisive reality can enter into the bosom of the Catholica. Therefore one should consider that the expression “national Church” — which is so often used in our day — is erroneous and even heretical, according to the definitions condemning phyletism that were pronounced by the Council of Constantinople in 1872. There is no Church of the Jews or of the Greeks, of the Barbarians or the Scythians, just as there is no Church of slaves or of free men, of male or of female.
There is only the unique and total Christ, the celestial Head of the new creation which is being realized here; the Head to which the members of the one Body are intimately linked. At this point any particular consciousness connecting us with any ethnic or political, social or cultural subgroup must disappear in order to give way to a consciousness “according to the Whole” (kath olon), a consciousness greater than the consciousness which links us with the aggregate of humanity.
In fact, our unity in Christ is not only the primordial unity of the human race, having only one origin, but the final realization of this unity of human nature which is recapitulated by the last Adam (Eschatos Adam).
This eschatological reality is not some kind of ideal “beyond,” but the very condition of the existence of the Church, without which it would be a sacramentalizing organism whose sacraments would have only a figurative sense, instead of being a real participation in the incorruptible life of the Body of Christ.