It is on these grounds that I have a real problem with a "closed table" Eucharist (or Lord's supper... we'll use Eucharist here). I'm worried about any prerequisite to the invitation to the table.
As Jurgen Moltmann has written,
"Because of Christ's prevenient and unconditional invitation, the fellowship of the table cannot be restricted to people who are 'faithful to the church', or to the 'inner circle' of the community. For it is not the feast of the particularly righteous, of the people who think that they are particularly devout; it is the feast of the weary and heavy-laden, who have heard the call to refreshment." (Church in the Power of the Spirit, 259).There are many theologians, many great ones (I think Alexander Schmemann fits this category) who believe that the unity of the table of the Eucharist is the unity of the "faithful," those who share a particular confession of faith, those who have a particular understanding of what's happening at the table (i.e. adults who have the capacity to understand the theology of the event and who are not sinning, in some serious way, against the fellowship of that gathering). Scenarios are cited in which a person does not understand what's happening or is living a life that directly contradicts the world that the Eucharist anticipates--namely, a world in which relationship to God and relationships among people are reconciled and where hungry bellies are fed. But I cannot help, with Moltmann, to see those scenarios as defining the table as a table preceded by faith, the faithful human response. In other words, wherever they place grace, it is faith and not grace that is determinative in the table fellowship.
In other words, since faith is what determines the unity around the table, it becomes "the feast of the particularly righteous." And faith becomes the prerequisite to the invitation to the table instead of the response to it. That seems to me to be the wrong order of things. (Side-note: this parallels my understanding of Baptism. Infants can be baptized precisely because it is grace, not their faithful response which is not yet possible but is anticipated, which determines and makes possible the invitation to the water.) When faith, i.e. a specific statement of faith or confession of faith, becomes the prerequisite, then the table becomes the Church's rather than the Lord's. We decide if they're in the club or not, if they're sincere or not, if they're righteous enough (or at least not too unrighteous).
The challenge here is that there was, as early as we can trace, a practice in the church (even for Paul) of "excommunication," of prohibiting some from the table, of withholding the invitation from some according to their ignorance and their unrighteousness. We even have Jesus giving authority to the church to bind and loose and, it seems, to excommunicate. That's there and we need to deal with it. But the only way I can imagine dealing with it is to take the authority and do what Jesus did with it... and Jesus invited "all who are weary and burdened" (Matthew 11:28), and Jesus also invited Judas to the table for bread and wine, even as he was already conspiring to betray Jesus. As for Paul... I think the situation was more nuanced than simple excommunication. It's important to remember that excommunication itself, in the early church, anticipated reconciliation. It was used for the practical purpose of bringing people back to the table eventually. I would say there are grounds for us to say that their practice had practical purposes no longer appropriate in our context for the communication of the Gospel. Whatever we do with those challenging passages, we should remember that we have as many examples of Jesus' radical hospitality (if not more) as we do of the church's exclusion of people from the table. If one is going to interpret the other, I'd rather listen to Jesus.
Specifically when it comes to the issue of righteousness, scenarios will be cited in which a person is sinning so radically against the table fellowship that their very presence undermines the practice. My initial (perhaps visceral) response to that is, "then I guess I'm out too." Which one of us can say that we are not sinning against the body? We are all sinners. All of us, by virtue of our sin, undermine that which the Eucharist anticipates and manifests simply by being present at the table, because the world anticipated in the Eucharist is a radically and wholly redeemed world without sin. We all fall short of the glory of God. All of us make the Eucharist fraudulent!
But that's where grace comes in. It is not our action--our righteousness or our unrighteousness--which determines the invitation. It's only ever God's grace that determines the invitation. And by that grace, we are invited before we are given the chance to prove or disprove our worthiness of the invitation. So while there might at times be practical reasons why someone should be dismissed (perhaps they're out of their mind), there are never theological reasons. Or, to put it more correctly, grace vetoes all the theological reasons why none of us should be able to approach the table and consume the elements.
The Eucharist, ultimately, is the presence of the future, "...thanksgiving is the experience of paradise" (Schmemann, The Eucharist, 174). It is the revelation of the world's true future which is, mysteriously, the grace which precedes our history. Whatever we bring to the table--our history, our disbelief, our sin, our ignorance--we are anticipating the redemption of it all. We are tasting the fruit of the promised land while we are here in the desert. And so if I am a sinner, I am invited to the table to anticipate my sanctification and glorification. If I am ignorant, I am invited to the table to anticipate my confession. If I am faithless, I am invited to come anticipate my faithful response to the grace manifested in Christ's body and blood in the sanctification of ordinary things like bread and wine (or juice).
This means that it's not just a laissez-faire openness, void of any critique or confession. It is, by anticipation, always necessarily and starkly a contrast to and a critique of the faithlessness of the world and the corruption it suffers. It is always painful for us, even while we're all invited, because it calls us to account. While the invitation precedes faith, it also anticipates it and even demands it. We are never off the hook. And in this way, ironically, the open table can be a more profound critique of sin than the closed table can be. For the open table never gives the impression that those who are partaking have, in some way, crossed a line and are now off the hook. They are never the "righteous enough" for the table but always and only the unrighteous who are lavishly welcomed only by grace and called into a world radically different from this one (but somehow still the same), a world manifest and anticipated in the Lord's (not the church's) open table of the Eucharist.