In the introductory chapter to his, The Eucharist: Sacrament of the Kingdom, the late Orthodox priest, Fr. Alexander Schmemann (+1983) lays out the rudiments of a Eucharistic ecclesiology very similar to that articulated by Joseph Ratzinger. Schmemann’s key assertion as he sketches this vision is that there is in the liturgy an
“undoubted triunity of the assembly, the eucharist, and the Church, to which the whole early tradition of the Church…unanimously testifies” (11).
That said, this unity has been broken apart, not fundamentally, but in the everyday understanding of clergy and laity alike. For Schmemann, such a reunification is the task of liturgical theology as it uncovers “the meaning and essence of this unity” between “the assembly, the eucharist and the Church” (12). The “assembly” or σύναξις is the first move in the liturgy, as it were. This assembling is the action of Christ gathering His people together for communion/κοινονια. So often, Schmemann notes, we look at the Eucharist through individualistic eyes, not seeing that the entire form/ordo of the Eucharist is a dialogical movement between priest and people. In particular, the anaphora or Eucharistic Prayer takes the form of a dialogical synergy or a working together of priest and people whereby they form “one organic whole.” Christ calls out the people from the world and forms them into an assembly to be united to Himself, to be the Church. When gathered together the assembly does not act on its own, but is united with Christ in the person of the priest. This unified working together (synergy) makes new what the Church is by renewing Christ’s unbloody sacrifice in the Eucharist and offering that synergistically to the Father. In the exchange of the offering the Holy Spirit operates in such a way that He both transforms the offerings into Christ’s body and blood and then works a similar transformative action (again, synergistically) on the assembly as they receive the Divine Gifts of Christ’s Body and Blood.
Ratzinger sees the same unity that must necessarily be accounted for, but accounts for it in a slightly different way. For Ratzinger, the covenant is the biblical mechanism by which the assembly becomes the Church. As Judges 20:2 expresses the connection between assembly and covenant: “all the tribes of Israel, presented themselves in the assembly [qahal] of the people [‘âm] of God.” Here, the qāhāl denotes not just a gathering, but a specifically liturgical gathering that is covenantal. It is covenantal because it does not just refer to the “people of Israel,” but to the “people of God.” This translation is unfortunate because it literally says, the “kindred of God” or the “family of God.” These familial terms illuminate the covenantal context because covenants create family bonds and it is in the context of such assemblies (in Greek, ἐκκλησίᾳ) that covenants are made. Indeed, when Israel is gathered for the business of the covenant, ἐκκλησίᾳ is the preferred Greek word to translate the Hebrew qahal.  In this light the ἐκκλησίᾳ or covenant assembly of Jesus is, Ratzinger argues, the place where the New Covenant is enacted: the Last Supper. As such, the remembering/memorial (Greek, anamnesis) that Jesus commands (i.e., ‘do this’) at the Last Supper is a remembering that is connected to ritual and specifically covenant ritual in the Old Testament. For Ratzinger, it is no accident that the only place the evangelists record Jesus using the word covenant is in the context of enacting the Last Supper. It is at the Last Supper where Schmemann’s triunity of assembly, Eucharist, and Church come together at their origin, as from a font. They come together again and again as the Church renews herself as the covenant assembly of Jesus at the liturgy of the Mass.
Both Schmemann and Ratzinger describe the same reality and see some of the same defects. Thus far in my reading of Schmemann it is not clear whether he sees this mechanism of covenant as Ratzinger sees it. Schmemann complains that the schoolmen of medieval scholasticism and their progeny have neglected this triunity of assembly, Eucharist, and Church. He is certainly correct. However, no less insightful was Fr. Romano Guardini’s penetrating recognition of
“how completely the idea of the covenant has vanished from the Christian consciousness. We do mention it, but it seems to have lost its meaning for us.”
Whether or not Schmemann sees this covenantal mechanism, he sees the Eucharist from the inside where Christ assembles the broken world and unites us to Himself in His offering to the Father. Schmemann recognized the rocks that the 20th century Liturgical Movement largely came to grief upon: “‘Our task…consists not so much in making various changes in our liturgical life, but rather in coming to realize the genuine nature of the eucharist.’”
 Balthasar notes that “‘Synergy’ expresses an inseparable yet unconfused interaction. Thus it is primarily christological in the sense of Chalcedon; but this first synergy yields a second, which is both its effect and its response, namely, that between the Spirit and the Church. Corbon calls the interpenetration of these two ‘liturgy.’” Hans Urs von Balthasar, Theo-Drama: Theological Dramatic Theory: The Last Act (trans. Graham Harrison; vol. 5; San Francisco: Ignatius Press, 1998), 416n8.
 The Hebrew “‘ēḏâ suggests the group or community, whether gathered or not” and is usually translated in the LXX as synagōgḗ. J. T. Dennison Jr., “Congregation,” ed. Geoffrey W. Bromiley, The International Standard Bible Encyclopedia, Revised (Wm. B. Eerdmans, 1979–1988), 761.