(1) Some reformed churches will require an interview from you (if you are a visitor) and then they hand you some sort of token coin so that you can show it and then you can then take communion during the service.
(2) Some churches will "fence" the table by declaring a solemn warning to those who partake by quoting 1 Cor 11:29 to ensure that those who take communion understand its significance lest they simply eat and drink judgment upon themselves. Along with this warning from 1 Cor 11:29, the minister will typically say something like... "if you have been baptized and are a member in good standing of a reformed or evangelical church, you may participate etc...".
(3) And other reformed churches will simply say something like this: "If you are a Christian, this table is for you. There is nothing more required to come to the table."
View (3) is probably the loosest and most careless approach to administering communion. There are absolutely no restrictions and the "requirements" are so broad that it can easy to fall into the trap of what Paul warns in 1 Cor 11:29.
View (1) is probably the strictest and **seemingly** the most biblically consistent, yet has great practical danger of preventing those to come to the table, say, for people who happened to come a little bit late to service at a reformed church and didnt get a chance to interview with the elders. And so it could possibly be argued that that church has now denied communion when it had no authority to do so.
View (2) attempts to strike a "middle ground" in that it gives the solemn warning of who can take communion, but for the most part, leaves it up to the individual. While the middle ground seems to be a good balance, this can be especially problematic for visitors who have not been baptized and are not members of any church, and yet willfully ignore the minister's warning and take communion. I have seen this happen before. I have even brought this up to the members themselves, and my admonishments were ignored.
View (3) does not make any attempt to do justice whatsoever to 1 Cor 11:29, and because of that, is clearly a practice that needs to be abandoned.
While view (1) and view (2) both have the same understanding of the theological reasons for communion and the requirements by the believer to come to the table, both have lent themselves to different practices that in certain situations can lead to certain practical difficulties. Those practical difficulties in and of themselves are not reasons for the validity of that particular practice, but it is something to be conscious of when attempting to administer communion. I personally would be comfortable worshipping at a church that holds to either view.
Regarding the outward practice of view (1) and view (2), they both presuppose that the member (or visitor) **must** be baptized and a member in good standing at a church before partaking in communion. Why is this significant? Why is this even necessary?
We understand that baptism is now the New Covenant sign and seal of the covenant believer (replacing circumcision), and membership in the visible and local church is a natural extension and visible representation of your membership in the invisible church. Baptism is something that is implicitly understood as being required.
Membership is presupposed when the NT letters talk about submitting to your church leaders, and praying for them, and when Paul talks about church correction/discipline issues in other parts of 1 Cor. One cannot be corrected by the church leadership if he has not formally acknowledged and submitted to that leadership through the process that we now recognize as the church membership process. A session (or consistory) would not start the discipline process on a one-time church visitor. If that visitor simply started attending the church for the next several months, is there anything inherently different regarding his status in relation to the church session compared to him visiting that first time? No.. There is no difference. Hence, this is why the attender would need to formally take that step in acknowledging the session's leadership in his spiritual walk and through this acknowledgement, he is now a member of that church.
It is important to realize that the way that the NT understands baptism and membership is that both are presupposed for every Christian to undergo. Those two things are so basic that it is unthinkable for the NT to consider a Christian not to have undergone baptism or formally submitted to a body of presbyters at a local church. For a Christian to not have done these two things is in fact a grave sin. It is amazing to me that the wonderful sign and seal that God gives us today is willfully ignored by many evangelicals and its significance and the seriousness of being physically set apart is not properly understood.
This is a big reason as to why the warning is given before communion for the partaker to be baptized and member in good standing.
While all of this above is correct, is there anything analogous from the OT that we can draw to support from?
In fact, yes, there is. If we look at Exodus 12:48, the Lord gave Passover restrictions to Israel, here in particular talking about foreigners.
"A foreigner residing among you who wants to celebrate the Lord’s Passover must have all the males in his household circumcised; then he may take part like one born in the land. No uncircumcised male may eat it. The same law applies both to the native-born and to the foreigner residing among you.”
For various theological reasons, I don't hold to the fact that the Passover is the OT "version" of the Lord's supper, although there are some parallels in terms of the foreshadowing of Christ in Passover and how Christ is fully revealed and celebrated in the supper.
However, what is clear is that the Passover was a religious ordinance that was commanded and the Supper is a religious ordinance that is commanded.
What was the requirement for one to participate in the Passover? If you notice in the passage, he must first be circumcised. And we understand that circumcision, in addition to being a sign and seal, also then meant visible entrance into the covenant community of Israel. This was a requirement for Passover for the native born as well as the foreigner who was not originally from the land. Notice that a foreigner was allowed to stay and participate in the cultural (civil) dimension and realm of Israel, and yet was not allowed to participate in the cultic (religious) dimension of Israel if he was not circumcised. (Among other things, this contradicts the false notion that "church" and "state" in Israel were merged.)
I think that it should become clear as to the parallels between the requirements for Passover, and how this carries over into the NT as it applies to the Lord's supper.
For those who were from the land (and eventually those who came as foreigners), it was presupposed that they would all be circumcised. Therefore, they would have received the sign and seal, and by default, the physical reflection of their receiving the sign and seal and therefore being set apart is to be (a member) in the covenant community (visible). Passover was a cultic meal that was meant only for the (visible) covenant community to set Israel apart from the Egyptians (at the time) that they belonged to God (among other things). Those foreigners who were not circumcised did not perform this ceremony in order to enter into the (visible) covenant community, and therefore, were not privy to enter into the covenant meal ceremony for those in the covenant.
In the same way, we should see that this concept of entrance into the visible covenant community (local church) is through the ceremony of baptism initially, and declaration of membership (say, if someone moves somewhere else but is already baptized), exactly the same intent as circumcision was in the OT.
Therefore, the foreigner in Israel who was not circumcised did not have the sign and seal, and was not physically set apart. Because of his non-participation in circumcision, he is not part of the covenant community (visible) and therefore was not a member of the covenant community, and was not allowed to participate in the covenant meal of Passover.
In the same way, a Christian who is not baptized does not have the sign and seal, and is not physically set apart. Because of his non-participation in baptism, he is not part of the covenant community (visible) and therefore, **should not** be a member of the covenant community (local church). So, he is not allowed to participate in the covenant meal of communion.
This understanding of the relation between baptism, church membership and communion is sadly not properly understood in light of what baptism and membership really mean, and more fundamentally, its OT basis.
Also just as sadly, there are many churches today who have no concept of baptism and have a weak view and sometimes flat out wrong understanding of what the requirements (faith AND baptism) are for membership. This leads to other practical, yet gravely theological at the same time, difficulties in which a Christian is a "member in good standing" at a church but has not actually been baptized. In this situation, the membership, while ***temporally*** valid with regards to that local church's membership requirements (simply a declaration of faith), is not ***theologically*** valid with regards to the biblical requirements of faith plus baptism. This Christian then moves to another city and starts taking communion at a church simply because he thinks that his membership is truly valid, when all this time, he is committing the sins in 1 Cor 11:29 that Paul so strongly warns us about.
May God continue to raise up godly churches that cherish and teach our sacraments and what exactly sacred church membership really requires.