Closed communion is evangelical and ecumenical. Open communion is legalistic and sectarian.
Closed communion is the practice of communing only those who have been instructed in the pure doctrine of the Scriptures. This doctrine is summarized in the six chief parts of Luther’s Small Catechism. Closed communion is the practice of giving the body and blood of Jesus in the bread and the wine only to those who confess this unadulterated Christian doctrine and have thereby joined themselves to the regular instruction of this pure doctrine at a congregation, which teaches this doctrine.
This practice is evangelical, because its presupposition is that it is possible and even to be expected that one can hold to the pure confession of the Holy Scriptures. The fact that we expect people to agree with the teaching of the Small Catechism and continually join themselves to this confession at a congregation, which teaches it, demonstrates something very evangelical. It demonstrates that we can – and indeed do – know what the Scriptures teach. The Scriptures are not an obscure rule book meant to be debated and interpreted by a court, a magisterium, or synodical resolutions. They are the clear, pure fountain of Israel, just as our Confession asserts (SD Rule and Norm, 3). And we, by the saving grace of God, know what they say (2 Tim 3:15). Therefore, insisting that people know this and publicly confess this is a confession that God is so gracious that he actually makes his Word clear to us.
Closed communion is evangelical because the practice assumes that the Lord’s Supper is a public, evangelical proclamation. And the gospel is to be proclaimed, not privately held under a bushel. As often as you eat the bread and drink the cup you proclaim the Lord’s death until he comes (1 Cor 11:26). That is to say that you proclaim the pure Christian doctrine of Christ’s death, which includes with it all parts of biblical doctrine. This is because all the Scriptures bear witness to Christ crucified for the forgiveness of sins to be received through faith (Acts 10:43). What we teach about the law, Creation, Redemption, how we come to faith and are preserved in the faith, prayer, baptism, the office of the keys, the Lord’s Supper, and even the table of duties – all of this pertains to Christ crucified. Denying what the Scriptures teach in any of these parts is an attack, from one angle or another, on the very essence of the gospel. Closed communion is a confession that all doctrine is united together in Christ. And it assumes that the gospel is not some privately held belief. It is rather something to be proclaimed from the roof top (Matt 10:27).
This practice is ecumenical. Ecumenical means that it is the practice of the church, the household of God, drawn from the Scriptures. The Greek word for household is oikeios, which is where we get the term ecumenical. It is ecumenical because it is Scriptural, and the church, the household (oikeios) of God, is built on the foundation of the doctrine revealed in Holy Scriptures, the apostles and prophets (Eph 2:19-20). It is therefore the historic practice of the church.
St. Paul rebukes the Corinthians (1 Cor 11:17ff) for gathering for the Lord’s Supper while there are divisions among them. This led them to abuse the Lord’s Supper, leaving some hungry while others got drunk. This was not a right practice of the Lord’s Supper, and Paul even says that it is not even the Lord’s Supper. This was because of their division. They didn’t agree on what they believed, as St. Paul admonished them (1 Cor 1:10). This division among them and thereby their abuse of the Lord’s Supper therefore caused some of them to get sick and even to die. The sin against the Lord’s Supper was taking it while not agreeing on doctrine and life. Because they did not understand that there was one Lord, one faith, and one Baptism (Eph 4:5), they all believed different things according to their own pet-teachers, whether that was Peter, Paul, Apollos, or even Christ (1 Cor 1:12). Paul therefore rebukes them for having divisions in doctrine while presuming to partake of the Lord’s Supper. He instead admonishes them to wait for one another, that is, be of one mind (1 Cor 1:10b), and then partake of the Lord’s Supper.
As I said, because closed communion is Scriptural, it was also the historic practice of the church. In the 2nd Century Justin Martyr writes concerning those who are admitted to the Sacrament:
And this food is called among us Εὐχαριστία [the Eucharist], of which no one is allowed to partake but the man who believes that the things which we teach are true, and who has been washed with the washing that is for the remission of sins, and unto regeneration, and who is so living as Christ has enjoined. (1st Apology, chapter 66)
Closed communion is also ecumenical because it does not ignore the serious issues, which divide the church. It fosters an ecumenical spirit, which seeks concord in doctrine rather than complacency. It shows concern for those who are in error’s maze rather than giving them the devilish impression that the false doctrine they profess isn’t really that dangerous.
Closed communion is both evangelical and ecumenical.
Open communion varies from congregation to congregation. Usually it involves communing those who can agree to their communion statement, which may or may not clearly confess the substantial presence of Christ’s body and blood in the bread and the wine. At the most it relies on the personal confession of the communicant, but it does not take into consideration where such communicant regularly attends church. In other words, it does not take into consideration what the communicant publicly confesses on other Sundays. Open communion is legalistic and sectarian.
Open communion is legalistic. Legalism is when one depends upon rules, whether divine or man-made, for comfort and certainty. Open communion is an attempt to fulfill the law of love. Those who practice it may often have some genuine motives, thinking that they are loving their neighbors who are caught up in error. But they are attempting to use God’s institution in a way that God has not given them to use it. They are, often unwittingly, attempting to win over their erring brothers by means of proclaiming that they are not really in serious error. By their efforts they have accomplished what Christ has commanded. They have loved their brother. Or so they think! But in reality they have taught their erring brothers not to avoid false doctrine. They have therefore taught them that they have met a certain standard, however low, which makes them fit to receive the Sacrament. Closed communion is practiced with the understanding that only faith in the promise of the body and blood of Christ makes one worthy. It therefore urges the communicant to depend on and learn from every Word that comes from the mouth of God. Open communion rather urges the communicant to lean on his own flawed understanding of God’s Word. Open communion urges one to rely on his own piety, rather than on the whole counsel of God (Acts 20:27).
Open communion is legalistic, because it treats instruction like a law to be fulfilled that makes one worthy for the sacrament. Those who promote open communion often assume that those who practice closed communion are legalistic. This is because they do not understand that instruction, or doctrine, is primarily evangelical. They look at doctrine as a burden. So, ironically, in their attempt not to be legalistic, they are treating doctrine as a rule book, which we must reduce to the lowest and most achievable standard.
Open communion is sectarian. If legalistic is opposed to evangelical, then sectarian is opposed to ecumenical. To be a sectarian means that one is not concerned about agreement in doctrine, but rather agreement in another manufactured purpose of some human institution. Often people assert that we are obligated as a synod to “walk together,” playing on the etymology of the word “synod,” which really just means a convening, coming together, meeting, convention, council, etc. Now, it certainly is true that members of a conference, synod, etc. should obligate themselves to confess the same thing. But is this what people always mean? If we mean that we are to walk together simply because we have agreed to be in fellowship, then this is sectarian. A sectarian is more concerned about some human pact to do things together than he is about confessing the same doctrine with other brothers. Those who promote open communion can boast all they want about their own congregation, their own synod, and their own fellowship. But if their main concern is not unity in confession of the precious doctrine of the apostles and prophets, then they are building with a different cornerstone than Christ.
If a congregation communes people without requiring that they publicly confess at other congregations and altars the same doctrine, then that congregation has claimed its identity in something other than doctrine. And that is the essence of sectarianism.
Open communion is the devil’s way of tricking weak consciences into affirming error. Closed communion is Christ’s way of leading us back to the truth and keeping us therein. While it may feel mean and unfair to our old Adam, closed communion teaches us to take doctrine seriously. And it urges our pastors to guard the doctrine, which has been entrusted to them. For by doing so they will save both themselves and their hearers (1 Tim 4:16).