What kind of unity is there between the ‘Church on earth’ and the ‘Church in heaven?’
Because all Orthodox Christians are members of the Body of Christ, no member can say to another, “I have no need of you” (1Co 12:21). Those alive on earth therefore cannot say they have no need of those who have gone to their rest, whose union with the Lord is beyond the reach of death: “neither death nor life… will be able to separate us from the love of God in Christ Jesus our Lord” (Rom 8:38–39; see Q376, Q402).
Whether we are “in the body” or have ‘put off this tent’ (2Co 5:1–4; 2Pe 1:13–14), the Lord Jesus Christ is “with us.” The promise of his presence and communion holds equally for the living and for those who await the resurrection: “Today, you will be with me in Paradise” (Luk 23:43; see Q118, Q167); “I am with you always, even to the end of the age” (Mat 28:20; see Q186, Q225).
This unity, grounded in the common relation of all to the one Head, our Lord Jesus Christ, and expressed in mutual communion with one another, is called “the communion of the saints.”
