Christianity= Eucharist + Church

For Christians, Sunday is the Lord's day. Sunday is the day we gather to celebrate the Eucharist. In the great exchange of the Eucharist, Jesus, by the power of the Holy Spirit, gives Himself to us body, blood, soul, and divinity as we offer ourselves to the Father, through Jesus Christ, body, blood, soul, and humanity, an offer that can only be honored by the power of that same Spirit.

This is expressed well by the prayer, said sotto voce by the deacon, or the priest, in the contemporary Roman Rite, when the water is poured into the wine on the altar during the Offertory: "By the mystery of this water and wine, may we come to share in the divinity of Christ, who humbled himself to share in our humanity."

Father Nicholas Afanasiev, a Russian Orthodox priest and theologian, who lived and wrote in the last century, insisted, to borrow the words of Fr Michael Plekon, "The Acts 2:44 description of the apostolic eucharistic assembly, epi to auto - 'always everyone and always together for one and the same thing' - becomes the defining characteristic of the Church" (Living Icons 159).

Plekon notes that Afanasiev identified the Church with the Eucharist "so radically as to become provocative" (159). As proof of this assertion, Plekon offers this from Afanasiev's book The Church of the Holy Spirit:

Christianity is the "Church of God in Christ." Whoever confesses Christ also confesses the Church and whoever does this, also confesses the Eucharistic gathering. Christianity apart from the Church is something that never was and never can be (159)

unus Christianus, nullus Christianus — "one Christian [is] no Christian."