In the RC and EO Churches, partaking of the Eucharist is as much an act or expression of one's union with the Church as it is an act or expression of being a member of Christ's body (and these churches may in fact view the two as being pretty much the same thing). RCs and EOs affirm, both in doctrine and in practice, that those who do not belong to these churches do not have the right or permission or ability to take the Eucharist in these churches, for such persons are not properly united to Christ such that they can partake of His body and blood. RCs and EOs are likewise not allowed to take communion with those who are not RC or EO, respectively. (And even though the RC Church and the EO Church have very similar Eucharistic beliefs and practices, RCs are not allowed to share communion with EOs, and vice-versa.)
Thus, in terms of their Eucharistic beliefs and practices, RCs and EOs do not treat or regard "other Christians" as full and equal members of Christ's body – i.e., as those who can share in their respective Church's and members' communion (κοινωνια) with the Lord (1 Corinthians 10:16). While this can probably also be said of some Protestant churches that have closed communion, in this post I'm primarily addressing the RC and EO Churches' Eucharistic practices and beliefs vis-a-vis the large majority of Protestant churches that simply require basic belief in Jesus in order to take communion.
In saying this I am not thereby saying that the RC and the EO Churches are wrong, but am only pointing out that their Eucharistic practices and beliefs are tied not simply (as is the case in many NSP churches) to the communicants' response to the question: "Who is Jesus?", but also to the questions: "What is the Eucharist?" and "What is the church?" Because of this, I think a person's view of the Eucharist should be an important factor in their decision to become or remain RC, EO or NSP. For example, if a person believes that:
- the bread and wine do or must become the Real body and blood of Christ (i.e., there is a change in the bread and wine),
- one's growth in salvation and/or reception or increase of grace includes the regular preparation for and act of eating and drinking the Real flesh/body and blood of Christ via the blessed Eucharistic elements,
- an apostolically-traceable ordained priesthood is a required component in authorizing and overseeing and effecting the sacramental change in the bread and the wine, whether by the priest's pronouncing the words of institution (RC Church) or by the priest's calling upon the Holy Spirit to effect the change (EO Church),
A Question: If Christianity from the beginning (i.e., from the time of Jesus and the Apostles) has clearly and unarguably always believed and taught and practiced points 1. and 2. above as a central doctrine and practice of the faith, can or should Non-Sacramental Protestantism be called "Christian"? I.e., can a "Christian" group which ignores or rejects something the earliest Christians (including Jesus and the Apostles) believed and taught as a central doctrine and practice of the faith really be said to be "Christian"? (I don't include point 3. because I don't think it is a requirement for believing points 1. and 2., or automatically follows from them, though history shows that this is how the church's Eucharistic practices and beliefs developed for the majority of Christians.)
Note that I am not saying that this is in fact what Jesus and the Apostles believed and taught, but only asking a question about what to do if this is in fact the case.
(I suspect that the RC Church and the EO Church teach either that this is in fact the case or that the church was led by the Holy Spirit to come to understand that this is what Jesus and the Apostles meant - and hence believe that their Church's teaching is the True Teaching of the Eucharist.)
For a book that says much of what I currently believe about the Lord's Supper, see Come To The Table: Revisioning the Lord's Supper by John Mark Hicks © 2002 Leafwood Publishers, ISBN 0-9714289-7-2. Though I find the book unnecessarily repetitive, Hicks confirms some of the main ideas I had concluded after much study of the relevant Biblical texts and the history of the Liturgy and the Eucharist. For more on Hicks and this book, see Thursday, December 01, 2005 Reflections on Come to the Table -- No. 1 (December 2005 archives) and Monday, August 08, 2005 Eschatological Table (August 2005 archives) at his old blog http://professingprofessor.blogspot.com/. FWIW, I had arrived at my thoughts and conclusions before I came across Hicks' book, which I serendipitously found during a visit to Half Price Books 10/21/08.